Ofcourse it is!
Nowadays, I notice most of bounties have strick rules, making bounties more organize and I like that Bounty Manager requesting Proof of Authentication to limit scammer .
It's been one of major mistakes of bounty hunter like me not to read rules and requirements of each bounties ending up not getting stakes so it's very important to read and understand each rules to ensure that we're doing the right thing and not wasting our time and effort.
It's very important to read the rules first and to check if the ICO is legit, you do not want 5 to 6 months of your effort go to waste, and I agree about the authentication, as much as possible I do not join a campaign that does not require authentication on social media and social content campaign, they will steal your works.