Pure speculation: I have to imagine they take further steps now as what is "no electronics" now isn't reliably what you can easily see now.
If you want to destroy a piece of electronics quickly put it in a microwave oven and hit start (also don't expect to eat from that oven later - plastic residue etc if it heats up that much is probably not safe to eat). This will destroy usb keys and storage on them, SSDs, laptops, smartphones and data on them. The only kind of data safe is magnetic type hard drives, but they become less and less common these days.
You could even make a kind of "wand" similar to what guys at the airport have for pinpointing metal items on people. Wave it around someone suspected of having a listening or recording device - job done.
So a bad actor would shield them? The primary countermeasure to incredibly small storage is minimizing the availability of devices that could write them on site. That microSD hidden in a nostril won't be of much use if the attacker does not find anything to plug it.
(regarding OP's story: I was kind of expecting it to end with the spaceballs password in heavy use behind all that physical security, still kind of disappointed/relieved)
So you'd have to pull some sort of slight of hand to manage that.
What would that do to, say, an artificial pacemaker? Feels a little, as you say, science fiction.
The "hard" part is really just getting the data off the computer in the first place, which is probably why they don't allow bringing in technology anymore.
I wonder how much of a micro computer could be smuggled in one or two parts at a time, stored in articles of clothing, with the intent of simply saving data to a micro SD card which would be the only thing you need to smuggle back out. You would need to be able to assemble the device without soldering.
I guess the easiest would be to build a digital camera to record the screen or photos instead of trying to plug into the computers themselves which probably have robust host intrustion detection and prevention. Or perhaps if you could just record the digital output of the computer before it reaches the monitor. That could be prevented with some form of HDCP though, I think.
This all sounds kind of like a science fiction movie (or In the Line of Fire or that Snowden movie) but it's an interesting thought exercise in any case.