Why?
This makes no logical sense.

https://www.sciencealert.com/swearing-is-a-sign-of-more-intelligence-not-less-say-scientists

What this collection of studies shows is that there is more to swearing than simply causing offence, or a lack of verbal hygiene. Language is a sophisticated toolkit, and swearing is a part of it.
The fact is that the size of your vocabulary of swear words is linked with your overall vocabulary, and swearing is inextricably linked to the experience and expression of feelings and emotions.
Richard Stephens, Senior Lecturer in Psychology, Keele University

If swearing is a sign of higher intelligence, you're saying that it's important they do not express themselves as they wish?

If you insult a really stupid person by pointing out their stupidity, this is a bad thing?
how so?
Insults can lead to thought. And thinking is good. Honest.

Important to who? You?