answer worked for me so I've got really nothing to add.
should I just post my answer anyway
If there's nothing to add, I don't think an answer should be added because it'll just lead to duplication.
Maybe give it a tweak or 2
If you can you can add answer an answer which is pretty different, then sure.
I feel like he gave the bounty and then just prevented me from getting the bounty. Is that fair
You arrive at this conclusion without even having posted an answer, not really sure how it makes sense. He doesn't know you're going to post an answer, he found an answer to his old question and posted an answer. Self answers are encouraged here.
Also, what happens if there is only one answer (that doesn't work) and his, how will he award the bounty?
It's up to the bounty started, either bounty is not awarded or if left as is, bounty will expire provided no answers which bounty auto awarded exist