How to achieve smooth surface on treated pine posts?
So, stupid homeowner mistake: we didn't specify to the contractor that we wanted smooth posts. While we were out of town, he installed these treated pine posts, and he went ahead and primed and painted them too (and yeah, I'm wondering if they had acclimated enough, but that's another problem for another day). When I saw them and asked him to smooth them out, he said sanding is risky and that they'll never really be smooth, but he's willing to try if we ask him to. He seemed reeeeeally hesitant, though, so I'm trying to make sure I'm not asking him to do something we'll regret.
I've done a fair amount of internet research on this and have read several Reddit posts that don't fully answer my questions. Mostly, the other Reddit posts on this topic are a debate between people saying "don't sand treated wood" and then other people saying "no, it's fine, they don't use arsenic anymore (but still wear a mask)." I also understand that wood filler doesn't really adhere properly to treated wood and will pop off over time.
We really dislike the super rough texture of these posts. So, what's the best way to salvage the situation? Ripping them out and replacing them is not an option, unfortunately.
Do we attempt sanding? My other (hare-brained, know-nothing) idea would be to buy some smooth, thin boards and just wrap each post in them so that they don't increase the size of the posts too much but provide a smooth surface. I'm not sure if those boards would need to be treated or not, or if it's even possible to obtain such material (would need to be 8' long to avoid seams).
What's the best way to deal with the jagged edges? Is there any type of wood filler that might at least hang around for ~5 years or so, and then we just accept that we have to have them redone every so often?
Thanks so much. Feeling very stupid over here and hoping someone has some encouraging ideas/guidance.