Check the rules, if it isn't there then it is maybe allowed ! Or you could also ask it on their Telegram if they have a bounty channel then it would be easy to ask it and get a answer.
There is an Ann thread that is dedicated to bitfence bounty here
https://bitcointalksearch.org/topic/bountyclosed-bitfence-remove-hackers-from-your-network-3270642
He could also ask his questions in the bitfence telegram channel here https://web.telegram.org/#/im?p=@bitfence
I have already participated in the bounty program and hope that I will get good BitFence tokens. But thanks for sharing the link here, it will help new visitors.