I spent 12 years of my life campaigning to get standing back. Every person against it was convinced bringing back standing would result in a revival of the skinhead movement, nazi tattoos on the forehead and the national front handing out flyers outside grounds. Stadiums would become war zones again.
Hasn't quite worked out that way.
I'm sure with CCTV in place, any fan knowing that they are seen chucking a pint of beer, or most likely piss, will see them losing their season ticket will be enough to prevent it.
You can't ban everyone from doing something because a few people may do it. Ban the pricks that do it and let the rest of us do what fans of cricket and both rugby codes do.