[Flatly:] Because it harbors the potential to infringe upon others' right to express themselves freely in any given situation. Because it caters solely to your own comfort level -- with the mere assumption that everyone else would remain comfortable with it.

It would be different if you said "no swearing around my person". That would be an addendum I would not argue against.

[Actually he wouldn't have argued against the no swearing rule in general if Edgeworth hadn't ruffled his feathers.]