Tom certainly shows restraint with Old Man Willow, which always surprises me because the tree DID try to kill some innocent hobbits. I'm not sure if he should have killed the willow or not, but it seemed more than a silly scolding was called for.
True, he does - but maybe that restraint is because he isn't judging or valuing Old Man Willow based on social rules; but he still helps the Hobbits. As an interested observer, outside of convention perhaps? Or because even though Old Man Willow is a bit rotten, he still values him as much as the Hobbits? So much of his song is about Old Man Willow - he seems to be an important part of Tom's little world.
He was more confrontational with the Barrow-wight and destroyed it (or close enough), but I'll argue that if Tom stands for what's natural, that imprisoned ghost of malice lingering in the world was NOT natural and needed to be sent to where nature intended for it to go.
That's a great point CG. You're right. Yes maybe the attitude is different because of the natural violation of the Wights. Plus when he looks at all the items he is sad, and seems to know who exactly was buried there. Maybe its a kindness too, to free them, especially if he knew and remembered them maybe (?)
I'll not say that Tom isn't a pacifist, but it was his idea for the hobbits to take the swords from the Barrow tomb. Quite practical of him, but not exactly pacifist, is it? Also true - but I think he is aware of the danger they will face outside of his realm, and also when he shares his vision of the Rangers with the Hobbits he is aware of Aragorn, and maybe of how Frodo and the Hobbits will be bound to him. If the Hobbits were to stay within his realm - maybe not so much enthusiasm for weapons. And if Sauron must be defeated for him not to fade away, last as he was first, he wants to stay where he is.

"Can we unite the two conclusions in that the Ring and Bombadil represent the opposite poles of empirical good and evil?"

Great point, Brethil. And interesting to think of Bombadil representing Good when normal depictions of Good tend to be stoic, ethereal beings (angelic choirs as just one example), not boisterous, silly beings like Bombadil.