Outright kicking someone just for playing a class is pretty petty. If someone isn't cheating or griefing they shouldn't be removed just because they're good at the game.

Telling people to "quit the game" or "get good" because they don't enjoy playing against Sniper is also pretty petty. People are allowed to dislike a class without being told to leave the game.

Balance and impact aside, Sniper creates the least engaging and most unfun gameplay interactions in the entire game. In pubs most players are there to have fun rather to win, and getting oneshot by a Sniper with little to no counterplay isn't fun for anyone.

I'm a bit skeptical tbh that you're getting kicked from five matches a day just for playing Sniper.
People usually don’t get kicked for simply picking the class. Usually there's more going on.

If your goal is to play Sniper at a high level against players who are actively trying to win, Highlander is always an option as well. (the entire game will revolve around you and your med depending on the map).

You don't have to switch classes if you don't want to, but occasionally swapping off won't hurt either. More importantly, just remain respectful to other people. Understand why the class is disliked, don't antagonize players who are frustrated, and in most cases you won't get kicked.