On one hand, protection limits responses to a question, which can work against the goal of the person awarding a bounty (assuming the purpose of the bounty is to elicit additional answers).
On the other hand, a question with a bounty may attract more bad answers from new users, which is what the protection is designed to prevent.
Somebody posting a bounty isn't, by itself, reason to change the status of a question. However, whenever you come across an older protected question, it's worth asking yourself: does this still need to be protected? Maybe it was protected because the question was on HNQ or Reddit or something and got a flurry of crappy answers; in that case, it's probably safe to unprotect it. (Any new answers will bump the question and then people can re-evaluate.) If the question is on a topic that could invite spam and has in fact done so, you probably want to leave that protection in place.
Protecting or unprotecting questions should be evaluated on a case-by-case basis. If something doesn't need to be locked down any more, go ahead and open it up.
It depends on the reason for the bounty.
In this case, the bounty is
One or more of the answers is exemplary and worthy of an additional bounty.
So it really doesn't matter if the question is protected or not - the person awarding the bounty already has a good idea of where it's going.
For bounties where
This question has not received enough attention.
We'd need to think again. But since the existing question has 12 answers already, I'd think that the question has certainly gained sufficient attention and the bounty-raiser can award the bounty as and how they see fit.
