With that said, you do have individual targets that are suspicious (e.g. https://citizenlab.org/2016/08/million-dollar-dissident-ipho...). There's always risk.
At that point, you'd have to hope the target would not check the hashes of update files. If detected, then there is the same issue: A signed malicious update being detected (and easily verified cryptographically if given to a reporter) would cause a catastrophic media firestorm, eroding trust in the vendor forever.
> With that said, you do have individual targets that are suspicious (e.g. https://citizenlab.org/2016/08/million-dollar-dissident-ipho...). There's always risk.
0-day use against perceived "high value targets" is indeed a possibility and valid concern. No argument at all there.
"We've revoked the signing key that was hacked by blah blah we have the utmost regard for security and adhered to best practices" and everyone would probably gloss over it for one instance.
I think you might underestimate the gravity of such a thing happening, it would not be glossed over.