We believe that your decision is excessive and abusive. Are you going to pay extra tokens for the bounty participants to compensate the long wait?
If not, I would recommend all bounty participants to go around deleting all comments made on all social media about your project, and posting a negative comment - such as you are refusing to pay them for what you own them.  Is there any agreement about not selling the tokens before your finishing your sales? If there isnt, you have no rights to hold their tokens and you should distribute right away. It is your problem that you distributed the tokens before the end of your sales. The bounty hunters did their job, now do yours and distribute the tokens.