To be fairly honest the only way of answering this is to ask them, however it just seems so weird that I assume that it is a hacker of sorts, and numerous other ORAS/XY online features have these people (passerby hackers with glitched profiles, etc). In conclusion this probably isn't some form of world wide event as the only thing effected is the GTS when searching for a Shaymin.
Sorry if this didn't really answer, but with the limited info I really couldn't understand the point of what the hackers are doing.
TL;DR: Hackers being hackers.
Hope I helped!