That's arbitrary conjecture at best.
A better explanation is that vulgar people will find ways to be vulgar in whatever language they're using, and it will catch on among other vulgar people.
Every human society has more-or-less arbitrary rules or fashions, and how closely our behaviour conforms to those rules reflects our social status. This is universal and almost certainly evolved over the course of our million-year-long dance of mate competition and selection.
Since social rules are fairly arbitrary (which we know because they vary so much) there are bound to be situations where it is useful to be able to signal we are moving outside them. Taboo words serve that function very efficiently.
This is a bit different from saying "We are hardwired to have taboo words", but it does show there are perfectly sensible ways to think about hardwiring in this regard, and it's a bit tricky to get away from.
One way of testing this hypothesis would be to look at the distribution of taboo words as a function of the strength and complexity of social hierarchies. I would predict that strongly hierarchical societies with more social restrictions would tend to have more taboo words and likely a finer grading of taboo words than more relaxed societies. On the other hand, if we are more directly hardwired to have taboo words, there would be no reason for the number or gradation to vary across different societies.
I think you're not understanding my "conjecture."
If profanity was purely something propagated by vulgar people, there should be a significant percentage of people where it doesn't trigger any negative emotions at all. Sort of like being "color blind" to shades of green or red, or deaf to hearing "15kHz" sounds such as cymbals.
We humans don't seem to have a brain that treats all phonemes and spellings as equal & arbitrary with no emotions which would render any attempts to create vulgar swear words to be an impossible task. So far, every culture and every language (even new languages) has swear words so I think it is very debatable whether vulgar people create that taboo or our brains already carry a reserved space for offensive communication. If so, that space is receptive for certain words to serve the purpose of offending it. Even if the brain/person has no desire to utter offensive words and further propagate them, they are still offended.
Of course, that leaves unexplained why many (all?) humans enjoy being vulgar...
That's also how comedy works, even without using any vulgar words.