Any decent SDR can notice such things, presumably not to mention actual EW equipment. It's only really with sub-noise-floor gold code type stuff where a signal doesn't jump out on a waterfall spectrum chart, and even then it's generally fairly obvious at close range. I can only speculate as to why that didn't actually happen here.
For "interference reasons"? Would you mind expanding on that?
On a university campus, let's assume that at least one of those channels is taken by the campus WiFi, possibly more if they have separate networks for staff or whatever. At that point, you start getting a few dozen private networks running in the dorms, and the campus network(s) grind to a halt.
I'm surprised that on Navy Ships, they're not using something of the sort, if only of the "Stalker Prevention" variety; Their EWAR systems should be scanning for APs that show up for more than a few consecutive days when not in port.
[1] https://docs.fcc.gov/public/attachments/FCC-15-146A1_Rcd.pdf
Fortunately PMF, a mandatory part of WPA3 but also available on some WPA2 hardware, should make these types of attacks much harder.
Metal panels between each deck and most of the walls, instruments and engines and microwave ovens running at all different times every shift generating RF noise... you almost need an extra repeater/access point for EVERY SINGLE ROOM and running on separate channels if you want it to be at all reliable.
Noticing an SSID is easy enough to work around. What's next? Can one easily scan for just radio activity on wifi bands? What if it was all wired, could the navy notice the unplanned RF signature (note that it's quite directional)?
Do military installations scan their RF environment regularly to notice such unwanted things?
I'd assume CIA/NSA/embassies do make similar scans, to notice surveillance gadgets.