Generally he has supported DSA-aligned candidates like Zohran
Supporting Zohran "homeless sweeps and bending the knee to Israel are good" Mamdani is effectively what I am talking about.
who in some capacity are trying to push democrats towards a proletarian party.
I hope you mean democratic voters because entryism is a dead end.
I didn't say he was blue no matter who, but pushing people to vote for "some democrats" is still channeling people away from the left. The other half of democrats who didn't "support attacking Iran" are still a part of the democrats, who funded genocide in Israel and promised to fund them even more. They will still go along with the war in Iran. They're still the problem. They are still a bourgeois party supporting the white supremacist, genocidal project that is the United states.
Specific candidates with left policies within the party are worth supporting
No the fuck they are not, because they are all literally on board with genocide. That's what joining the democratic party IS. These are people who are explicitly choosing to align themself with an organisation that has the explicit, stated goal of supporting and funding the genocide in Gaza, among many other unforgivable crimes.