Even distribution seems to generally reset spoilage times on things you use it on. I have seen this happen with:
-Distributing bioflux into biter spawners, the bioflux becomes fresh.
-Distributing semispoiled nutrients into biochamber fuel slots. Nutrients become fresh
-Distributing yumako mash into biochambers as an ingredient, it also becomes fresh.

I've also experienced this with Biter Eggs, which means you can effectively keep chests full of them indefinitely so long as you remember to come back and distribute them again into other chests every 28 minutes.

Ran into this is a modded Pyanodon's playthrough. Of note is that if you have some boxes full of a spoilable item, and you use the "balance inventories" mode to drop one or two more into them, every single item in every box has its freshness bar refilled completely.

Bumping this as I've run into the same issue. My biological science arrives on nauvis about 60% spoiled, but when I Evenly Distribute them into labs, they are back to 100% fresh. I'm not really complaining too much.. but it's definitely a bug.