It sounds to me like you're arguing that full disclosure in this situation could lead to a worse outcome for users in the short term, but the negative publicity will force Apple to improve their security posture, leading to a better outcome for users in the long term. (Please let me know if I'm miss-characterizing your argument)

I think you have to be very careful about that line of argument. It's a single vulnerability researcher making a unilateral decision about the short term and long term security of an entire user base, based entirely on personal judgement. I personally think the researcher should make the decision that best protects users from that specific vulnerability. Making long-term changes to a company's QA should come second.

> I personally think the researcher should make the decision that best protects users from that specific vulnerability.

I find it odd that you're putting the responsibility of making decisions about how to protect Apple's users on an unaffiliated third party.

Apple has a multi-hundred-billion dollar war chest and, if they wanted to, could afford to make macOS the most secure operating system on the market. The fact that they don't is their own choice and a reflection of their priorities, not some act of God or a natural disaster. Putting the onus for cleaning up the mess in the most "responsible" way possible on third parties with a fraction of Apple's resources is being too kind to Apple.

My point was exactly the opposite of putting the onus on the researcher. I support responsible disclosure. In responsible disclosure, the researcher informs the vendor (Apple) and leaves it to them to coordinate informing people of mitigations and pushing out a patch. If the vendor fails to respond or make progress in a certain period of time, the researcher can inform the public. It specifically puts the responsibility for dealing with the vulnerability in the hands of the vendor.

I think only economic consequences would cause Apple to up its QA game. Like decreased sales or lawsuits with good prospects of winning serious money.

Unfortunately, I don't believe those will happen.