Rest assured, any decent manager would know that 'reputable members' won't spend their time bounty hunting or using altcoin sig which is not guaranteed when they'll get paid.
Yeah, but the problem is that bounty managers tend not to be reputable (at least the ICO-related/altcoin-paying ones), nor do I think they would waste their precious time verifying whether a registered member's username is actually the person who's participating in the bounty. I'm not quite sure how someone would get more stakes just by entering a random Legendary member's name into their application. If that's actually happening, then there definitely need to be some checks and balances in the application process.
If you're bored, try asking the bounty manager to change the address to one you control

this... may be the only way to stop the pajeets doing it.
LOL. That would be fantastic if it worked. It'd be like throwing a shit-pie in a scammy bounty hunter's face.