As with a discussion in another thread, the “who determines . ” has a simple answer: the community. We determine what constitutes “foul” language.
The constant use of such language is seen as a negative. Justified or not, it calls into question the intellectual quality of the user.
In this community, in these forums, the constant use of what this community perceives as “foul” language will get you ignored. Right or wrong, the point you are attempting to convey, no matter how compelling it may seem to you, will be degraded by your language and may indeed be lost.
The communicator has the ultimate responsibility to assure the audience has received the message. Anything that detracts from this effort is an abrogation of your responsibility and is seen as intellectually lacking. The constant or inappropriate use of foul language makes one look stupid. Here at EvC, stupid is not good.
As has been pointed out up-thread, the use of a well placed swear can be a powerful communication. Overuse, however, is detrimental.
And if you cannot except this then go (expletive deleted) yourself.
(Kinda dated myself there, didn’t I)