Because I didn't think it was important to address. Giving up a seat on the security council would be stupid, in case it ever actually has teeth. It's also good for diplomacy on the international scene. There's no scenario where China would abandon the seat.

As for abstaining being a vote for, no. Vetoing would not prevent the US from continuing with their plan, China abstained and stated their actual stances, pushing for Palestinian statehood and not disarming. UNSC resolutions don't really have the power to stop the US Empire.

Would I rather China have veto'd? Yes. Does abstaining make them equivalent to those orchestrating and fueling the genocide? By no means, at worst it means they aren't sufficiently anti-imperialist, in no way does it make them imperialist.