If you’re a terrorist, I’m pretty sure you can think of dramatically more consequential things to do than cause a handful of planes to potentially divert. That’s a wildly pointless prank for something that will invariably wind up with you being arrested.
Why do that when you could simply attack people waiting in the security line? That would actually cause terror and shut down an entire airport for days.
A saboteur might want to cause disruption without violence against people, and such cases would still likely be labeled terrorism.
Only because we have labeled anything and everything terrorism these days.
Even then this is an extremely lame and ineffective form of sabotage, compared to the kind of prison sentence you’d be risking.