So your statement just seems to be your bias thinking that a slime mold couldn't possible do any reasoning. Cells are much smarter than most thinks.
Edit: Anyway, apparently slime molds can communicate what they learn by sharing those proteins. So they do have a language, it is like a primitive version of how human bodies cells communicate. So your point still stands, reasoning seems to go hand in hand with communication. If you can reason then it is worth it to share those conclusions with your friends and family.
They also taught slime molds to cross a bridge for food, and it learned to do it. Then they got the slime mold to tell other slime molds and now those also knew how to cross the bridge. It is pretty cool that slime molds can be that smart.
https://asknature.org/strategy/brainless-slime-molds-both-le...