I have experimented with this in a 3/4 bath with a small counter of "hevea/rubberwood" treated with MinWax pre-stain, then Minwax stain, then Minwax Spar Urethane. It hasn't seen a lot of use yet, so I don't have much to report, other than that the spar urethane seems a bit delicate/easily scratched.
I am considering using this same butcherblock product in the main bathroom and even in the kitchen -- which of course takes a different food-safe finish with mineral oil and so forth.
In the main bath, I'm leaning toward trying a real spar varnish, either Rustoleum of McCloskey Man-o-War. Anyone here have first-hand experience with butcherblock in these wet and or food prep places?

It is bound to go bad eventually.

Granite will never need refinishing, nor will it ever go bad.

^^^

Even garbage granite will last longer than BB.

Only way I would do butcher block in a bathroom is of using a vessel sink so there is less chance of water constantly getting on the wood

Read somewhere recently butcher block is making a comeback for kitchen counters.

We put a vessel sink on an antique cabinet with a wood top 19 years ago during a bathroom remodel. The counter still looks like it did when we installed it.
This is in our downstairs bathroom that is used more than any other bathroom.

We have it on our kitchen island and love it. Would’ve done it on all my kitchen surfaces if my wife wasn’t set on granite. If you take care of it, it’ll last a long time. And by take care of it, I mean oil it down every 3-6 months. That being said, I don’t care about it looking perfect. I chop on it, tenderize steaks, whatever. It you want your countertops to look perfect, go with what most of the others will probably say.

Sauerkraut, when you say oil it, I assume you mean food-grade mineral oil?

I use tung oil. Give it a really nice finish.