I do dendrochronology (consists basically just staring at hundreds of tree core samples and analyzing them), and I'd guess that that's a hardwood. There's a chance it could be some sort of uncommon or foreign decorative softwood though, so I can't be 100% sure, esp. without bark.
When you sand it can you smell anything? Again, it's not 100% certain but you'd probably be able to smell the oils if it were pine/cedar/other softwoods.
Edit: Looking again, that may have come from a shrub and not a tree. If so, my guess would lean toward crape myrtle or something in the laurel family. I don't know which shrubs have oils that might bother a snake's respiratory system though.