Typically swear words are uttered during a lack of self control, which is sinful. Being very deliberate in this case shows that it was not.
Meekness is specifically having the self control not to punch the other guy in the face, not just being submissive. It appears in proverbs and the sermon on the mount.
You probably don't want to know this, but people with autism commonly don't have regular bowel movements, so…