Dunno if anyone else has noticed this, but the filter options only affect your text.
For some reason, even though my filter is off, I still see comicified swears and other people can see when I swear because my filter is off.
Unless it's some kind of conspiracy and people are pretending to comicify swears and see mine, this might be worth fixing.
I think what you're saying is correct. To my knowledge if your chat filter is off others are able to see your expletives and if it is on others cannot. I haven't bothered testing it, since it doesn't honestly concern me, but I just wanted to bump this and agree with you.