You know i assumed that was true until right now. But I can't think of a single example of reason and intelligence existing without any form of language. Even insects have rudimentary language, and in fact reasoning and intelligence seem to scale with the complexity of language, both by species and within species.
Do slime mold have a language? Slime mold can learn and adapt to environments, so it is intelligent and can do rudimentary reasoning, but I doubt it communicates that information to other slime molds.
It is a very different kind of life form though so many things that applies to other complex being doesn't apply to them. Being a large single cell means that they learn by changing its proteins and other internals, very hard for us humans to reason about and understand since it is so alien compared to just having nerve cells with physical connections.
Not sure i would say a slime mold has reason and intelligence .. Or if i would then so does a river. Also i think that how it changes its proteins could be considered a language, without stretching the definition of language any more than we have already stretched the definition of reason and intelligence.
Why is a slime mold a river but a human isn't? Slime mold can predict temperature changes in its environment and react before it happens, that isn't something a river could do.
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.
