Clearly this is an edge case and I probably shouldn't have even tried awarding the bounty to a deleted answer, but why is the bounty award button even available?
It's not a bug since someone added in the notification seen in the final image. But that sure seems like a roundabout way to let the user know that they can't award a bounty to a deleted answer. The second step is particularly strange since the system really ought to know that the warning is pointless: no bounty can be awarded. My suggestion is to rip-off the Amazon 1-Click patent and let bounties be awarded without the warning. Then remove the single click button from deleted answers.