the Oval Office doesn't have start/stop genocide button

True, but it DOES have the option to stop supplying bombs that they know for a fact are being used to commit that genocide.

Your "either they can push a magic button or they're doing all they can" dichotomy isn't clever. It shows that you're being either disingenuous, willfully ignorant or just extremely obtuse.

Because the problem is systematic

Yes, Israel is systematically wiping out the population of Gaza and the Biden White House is using the levers of the system to help them do it. That's not an argument for not telling them to stop.

You can't just uproot the US-Israel nexus that's deeply entrenched in the US politics

You can, in fact. It worked with Apartheid South Africa, which the US also kept supporting way beyond the point that most other countries stopped, and it'll work with THIS apartheid regime too.