A watering-hole as large as Twitter will be under constant attacks of every sort and every source, from individual white/grey/black-hats trying to poke holes in

A watering-hole as large as Twitter will be under constant attacks of every sort and every source, from individual white/grey/black-hats trying to poke holes in the service itself, spammers who want to figure out how to create as many automated accounts and tweets as possible without getting blocked, government-sponsored hackers trying to get personal information on dissidents or defectors, etc etc.