A Question regarding Leaving during Champ Select

So, is it bannable to leave during Champ Select? Ya see, I really want to play this specific champion and so I go to draft pick or blind pick, but there's always that one guy who has some kind of freakin' I dont even know what he has but apparently it connects so fast he can say "mid" before the game can even say everyone has joined the lobby! It's so annoying! So yeah, I kind of got off-topic. Is it bannable to leave during Champion Selection? I want to play a specific hero, but I cannot due to the fact everyone is taking the lane that I always want to go to, that lane being Mid. I know it gives me a 5 minute penalty and stuff, but is it bannable to keep doing so repeatedly until I get the lane that I want? or is the only punishment the 5 minute leave? I can assure you that I don't leave to cause a small inconvenience for other players, (that's just stupid.) I just leave because I want to play a specific lane.

Thank you for your time!