If you deny the player the chance to use his ability at a point where the trigger has passed, BUT the game state has not changed in any meaningful way, you are not flying casual. If you then go online to complain about it, it's also not flying casual.
In saying that, your opponents snarky response wasn't called for either.
The point of fly casual is to treat people with respect, to allow them a bit of leeway when coming to gripes with all the different triggers and rule interactions, and ultimately to have fun.
It ultimately sounds like a very minor disagreement between 2 people with poor conflict resolution skills.
