I don't have an answer about how safe the wood is for your snake however Ball Pythons are not arboreal and mine are kind of clumsy when they do climb to any height. I have fake plants in my tank but I would be worried about them falling if I had branches for them to climb on.

We have two ball pythons and as long as they have something to hide in they seem pretty content.

I say skip the branches and save the hassle of drying and sterilizing them.