I have found a similar MSO post for reinforcement.
This is a very good question. Of course, we cannot stop a user from starting a bounty. In this case, the OP insists that the code works, but the community thinks otherwise. Whether or not close votes come in, anyone can still provide an answer, which will very likely be an overall review and not a fix. The OP could still choose to award the bounty if it's helpful enough, or continue to wait for the type of answer that he/she may not receive on this site.
Overall, I think it's best to flag a moderator. If it is that the code indeed does not work, based on community input and/or personal knowledge, the bounty can be refunded. Another option before this refunding is getting the community to edit in the fixes, and I've seen this done before (but not on a regular bases). Now, if there are a lot of needed fixes, it may be best for SO. This would then leave the bounty period to continue to expiration while the post is closed. Or, the bounty could still be refunded, then started again as soon as the code is fixed.