Why do you believe that? Apple made quite a lot of news by refusing to unlock the iPhone 5C from the San Bernardino shooting. Helping nation state actors find vulnerabilities would be contrary to their previous actions.
Not really. Helping nation state (any) actors gain access to user data would be contrary to their previous actions. Helping experts research vulnerabilities is a calculated risk that the good guys will reveal bugs at a similar rate or faster than the bad guys, whilst also disincentivising the hoarding.
I don't understand. vuln seemed to be suggesting Apple would give pre-jailbroken devices to governments to find vulnerabilities with instead of giving them to established white hat researchers.
I don't see how that would help good guys reveal bugs.