If I change my champion when it's my turn to pick, why do I get a dodge because the lock button lag?

Seriously, if I change my champion when it's my turn to pick, why do I get kicked as a dodger? Why does the lock button not register if it's down to 3 seconds or less? If the champ is changed from the "I want to play this selection" then how can the person be afk? lol just saying