John K Jordan
Latex paint is not effective for sealing. Hot wax or wax emulsion (AnchorSeal) is much better.
I almost always seal just the end grain in hardwoods. White pine, I don't know, maybe someone does.
A log or half a log will not dry much in 6 months but maybe it doesn't need to be well dried before using it. Cutting it in half first may help minimizing cracking, although in my experience white pine doesn't warp and crack as readily as many hardwoods. However, my experience is only with boards and slabs cut on my sawmill - not sections of logs. In general, whole logs don't dry inside, at least not in a reasonable time. Here is some discussion about drying logs:
It does get attacked by bugs so removing the bark as soon as possible and getting the sections inside as soon as possible might help. I might consider saving several pieces as alternatives in case the first one doesn't work out.
Since it won't be kiln dried, you may have to deal with the sticky mess of unhardened pitch, depending on the tree. What one guy does: https://wunderwoods.wordpress.com/2011/10/04/sanding-white-pine-avoiding-a-sticky-situation/