Realize you're talking to folks who do this kind of stuff for a living, rather than just the random Internet denizens of most other websites.
The FBI will regularly inform and assist companies who've been breached, for example. The US government is very interested in protecting US companies.
That said, they don't quite have any guidance from congress on how to do that, so right now the assistance is limited. It is most certainly there, however, and your tinfoil-hat nonsense doesn't really fly.
Then one day one of the people we had the identity of boasted on how he had briefly brought down the website of one of the democratic primary candidates. We forwarded that information and our case was reassigned to another agent and the person was arrested immediately. I absolutely think it's true that the US government is only interested in protecting established and powerful figures. I suspect the reason is career driven - defending the little guys isn't glamorous and probably has no promotion impact.
Your other responder works in this field, and I have been on the other side (worked for a company that got this sort of help). We also regularly had the FBI come in and give talks on the sorts of things they were working on in this space.
The US has no interest in saying "international cyberattack should be illegal" because then other countries might insist that it stop. They could go for a trade war escalation, but that would at some point have Apple as a casualty.