So last night I was flying a swarm against dual IG's with advanced sensors. He reveals his dial, sets the template down in the front nubs of the ship for a 3 Segnor's, and before he moves the ship he attempts to declare a TL. I don't let him because he has already revealed a dial and measured the maneuver out.
He says, "Oh, so you want to play /that/ way? It's a casual tournament and I'm a new player".
After I can see how angry he is and how few people show up to the newly founded Thursday X Wing $5 tournament at this venue, I relent and allow him to do it, he angrily refuses to take the TL I allowed him to take, and then I again make it clear I'm fine with him doing the TL so he does it. When it comes time to go to the firing phase the ship he TL'ed isn't in arc of the IG he says something like, "See, it doesn't matter anyways".
This player was a beginner, but he isn't super new to the game and he's played dual IG's a few times before. By now he should know his triggers.
1.) Unless someone is super new, as in first handful of games, I'm of the opinion that it's okay to deny forgotten triggers because they should know better by now. Also, it helps their play because once someone is denied a forgotten ACD for example, they won't ever make the mistake again.
2.) I don't understand why someone would get so angry about it. When I'm denied the ability to perform forgotten triggers I see it as a fault in my memory and not the fault of my opponent for not being lenient.