I don't think they don't want people saying "assault" specifically, but their profanity filter is just lazy coding. It should have exceptions, and obviously "assault" is top on that list. I too had that problem, as I always name my sub-machine gun class "heavy assault". I don't want to call if rifleman, that doesn't even make sense.
Whoever coded the profanity filter obviously didn't give a damn about making it reasonable, neither did the testers, neither did the company executives. It's embarrassing really.