The thing about bug bounty programs are that they are not a negotiation. They decide how much your information is worth--take it or leave it.
If you thought this bug was worth $25,000 and you feared that Apple might offer a $100 discount coupon plus a lovely "I Love My Mac" coffee mug, is there any way to start a negotiation without being accused of extortion (if you imply that you might disclose it publicly)?
This is a serious question: Is there any way to negotiate for security bugs, before or after disclosing all the details, without running a legal risk?