I have no problem with people taking off-supports bot lane as long as they make a good-faith effort to actually support or otherwise explain their strategy and the reason their choice could work. If they're not a fit for your team, KICK THEM. It's that simple.
The bigger problem IMO is people queuing as typical supports and then just taking all the CS and trying to carry. Fake supports that only queued as support so they could get a game faster, then ruin the game for their team by running a completely different strategy than they said they would. Most people will accept them onto the team and there's no way to detect that behaviour before the game actually starts.