When you hear "Obstacle Obstacle" announced in Sully, that's not a radio altimeter detecting the bridge, the computer has concluded that the plane's motion is uncomfortably close to the bridge tower based on GPS and a database of tall things you might fly a plane into (and thus it knows this is an "Obstacle" whereas a mountain is "Terrain").
In that movie there's not a damn thing they can do beyond avoiding the bridge itself, because they don't have any thrust - but ordinarily pilots should near instinctively try to ascend immediately for any of this group of warnings. The training is specific that this is not the time for diagnostics, if you aren't already absolutely sure why the computer thinks you're about to hit something you must assume the computer is correct and climb at best rate. This routinely saves lives when pilots become confused about where they are.
From my not-very-informed perspective US competitors don't need to catch up to Chinese equipment, the Chinese equipment makers are locked out. If anything the US equipment makers would have the OPPOSITE motivation, get the spectrum sold and get their sub-standard equipment into the networks before the position of the US government could possibly change and they face real competition. And that is kind of what is happening, right? The actual story here is the FCC (lead by carrier and equipment friendly folks) are seemingly pushing ahead despite concerns from other industries, no?
Also, not so long ago there were "reports" claiming Huawei devices were compromised and no evidence was provided. The negative marketing against China has been candid and in the open. The US is just trying to win in the court of public opinion on several fronts.
So yeah, "The military is scrambling to understand the aviation crash risk from a new 5G sale" and don't provide a technical basis for the concern: it reads propaganda all over.
And around the world 5G is not being deployed at the same frequencies! They are concerned about a particular spectrum. Lots of the purchased spectrum as I understand it is 30Gz+, they are raising zero concerns about that.
Is this frequency congested anywhere in the world with or without 5G technology to test?
Just this year Kobe Bryant died because his helicopter impacted the terrain.
If this happened after the sale, you'd have to do just as difficult of an analysis to prove that 5G frequencies did not play a role in the impact, so why not do the analysis before hand?
As to Kobe Bryant, yes his helicopter flew into terrain (unsurprisingly, 'flew into terrain' is incredibly common in aircraft accidents. Sadly, most of them are perfectly serviceable when they do so). There is no indication that the issue was a radar altimeter (if one was even installed, I don't believe they're required in that class), much less one that was being interfered with. I don't think the NTSB report is out yet, but I expect the cause will be what it commonly is: a pilot (with a famous and rich client who wanted to get somewhere quickly) taking their vehicle into marginal weather conditions beyond what they and their aircraft are competent to handle. Working on that problem will save a hell of a lot more lives than investigating 'may be a problem' that no one can even describe a mechanism for.
Existing synthetic vision systems would have easily prevented this. They're not even that expensive - built in systems can be had for a few tens of thousands of dollars, or non-certified iPad based systems for a few hundred.
That crash was likely due to disorientation in dense fog with an experienced, IFR rated pilot but who didn't experience much fog in LA. A radar altimeter would have been unlikely to help.
Radar altimeters use vastly more power than anyone would waste on mere communication. They also don't depend on subtle variations in the signal to communicate. It's basically just listening for a return and measuring time-of-flight. Timing measure is more complicated, but doesn't depend on subtleties of the signal that could be easily interfered with. (Full disclosure: I've worked on Herc terrain-avoidance radar, but that was forty years ago.)
Note also that commercial aviation pilots don't use terrain avoidance radar in normal flight operations. It's an emergency system. If you're low enough to need it, you're supposed to have an airport in sight. If you start getting the "Terrain. Pull Up" warning, several things have already been going wrong for a while. If you blocked the TAWS system of a commercial airline in normal flight, it's unlikely they'd even know it. You'd have to wait around for a lost or damaged aircraft that was already about to crash, which is a pretty unrewarding hobby.
To be honest, I'd be surprised if the military didn't already have a pretty good idea how to spoof terrain avoidance radar, it would be the kind of thing that might be nice to have in a special operations toolkit. But I doubt it looks like sitting on the end of a runway with a cell phone. More like humping several car batteries, a dish antenna and a Halliburton case full of electronics to the top of a ridge. (Which, another thing: terrain avoidance radar is the opposite of stealthy, you wouldn't use it for special operations, especially when you have access to GPS, satellite maps and inertial navigation systems).
Even a 5G transmission from ground to geosynchronous orbit would be columnated by a dish, so would only interfere with a moving altimeter for a fraction of a second, and those systems are designed to handle transients. I'm not saying there isn't a potential issue, I'm saying you're not going to find out if you limit yourself to interviewing bureaucrats.