children/adults with SEN and no speech can always swear .ive worked in this fieldfor 20years and also have a 36 year old who dosnt have any speech or noises at all never has had. last night just as he was recovering from a tonic clonic seizure, he took a bout of the sneezes and just as he was about to sneeze he shouted very clearly at the top of his voice OH FUCK, this happened about 5 times before he fell asleep due to him having recieved his emergency meds , this morning i was joking with him and telling him about it and he just smiled, there has been nothing else today.
My mum has alzheimers, and often in the latter stages they get very angry - aggressive and verbally abusive. apparently anger is the last emotion to leave them. so now that she has no recollection of who i am, and very little pleasure in anything in her life, she still shouts angrily if someone makes a noise she doesn't like. Just a thought, but maybe neurological problems with speech are the same. it is easier to elicit communication in anger than the other emotions?
It's because swear words are created in a different part of the brain to normal speech, this article talks about it although it doesn't explain it particularly well, imo, but just off to cook the tea, quickest I could find.