Earlier quoted context omitted.
Cheating the location on my phone is gravy. Broadcasting an RF signal to spoof GPS (and especially across a campus), that my friend, is not trivial or cheap.
Trying to set up an alternate 3d volume of GPS space sounds very difficult. But broadcasting a loud signal that tells everyone in range that they are at the same exact point doesn't seem too hard to me. Couldn't that even be as simple as replaying a single-antenna recording taken somewhere else?
Yes exactly.
Doesn't work well with some receivers that cache data from the real network and stay locked onto the much weaker real signal. But works with most receivers.