Palestine has attacked territory that was assigned to Palestine by the UN in 1947. The UN also makes it very clear that a country may lawfully recover occupied territory "by any means, including armed force". UN laws are thus very clear: Ukraine and Palestine can recover territories by force. Now, that doesn't mean you should support them in their struggle to do so, but if you don't, it must be for some other reason (e.g., Israel taking over would constitute a huge strategic gain for the US, while Russia taking over would destabilize the world and thus benefit small or weakly aligned players).