Some people are banned for life no doubt, but the response here is that people can always email to request being unbanned, for example chrux and nation recently were unbanned so there is hope.
The reason Clerics get 250 offense is because their main form of dps is from melee (yaulp6 and summoned hammer). druids get cataclysm and a dps pet as well as other nukes and shamans get powerful dots and the murk bear form.