This is only going to penalise genuine users whilst giving advantage to bots who can automate the process. Theymos is never going to do anything that is this restrictive so we need ways that only effect the bots.
Something like adding a simple captcha to brand new/newbie accounts before posting?
It'd be a bit of a pain, but it's not restrictive, and most already do that on faucets, so doing another one to send the bounty report won't really matter to them. Bot owners could of course pay for the services that solve captchas for their bots, but it could reduce the number of bots (or so I want to believe).
The "only" downside I'd see is that depending on the captcha type, it wouldn't be very TOR friendly