I don't know what the training is like for being a character at Disney World, but I imagine savagely roasting guests was an ad lib. Gaston gives precisely zero fucks.
The more I watch this video, I actually think Gaston was trying to imply he was looking for Belle — because the adults walking around in the 100-degree heat with screaming kids all around are supposed to believe they're actually in Beauty and the Beast or something like that. But with what he ended up saying, he absolutely eviscerated this girl in front of thousands of onlookers. Extremely tough scene.
But honestly, if you're looking for some sort of romantic affirmation — real or not — from a guy dressed up as a character from a 90s animated movie, you deserve whatever that dude says back to you. And I'm actually glad Gaston said what he said. The Disney adult calling out to characters needs to be put in her place.
And there is absolutely nothing wrong with going to and enjoying Disney as an adult. I would go tomorrow and have a great time. But there is something wrong with you if you get excited to see characters and try to do weird shit like this. Go ride Big Thunder Mountain like a normal person.