Lets talk about that assumption for a moment though. I'm sure there are some rational actors remaining in Ukraine that independently wish to defend their land. But I doubt any of them are fighting to defend their religious freedom. Because Ukraine doesn't have religious freedom. Kiev doesn't allow it.
Now let's assume for the moment that there are rational actors in Russia that independently wish to defend their land and their way of life and they believe that NATO has been slowly inexorably marching on Moscow, but they want military support. Would you be against sending them weapons? And if so, what is the difference between Ukraine and Russia that makes your opinion change when the actors of your hypothetical are swapped?