I'm not sure why you keep acting surprised that this is "allowed." As far as I can tell the only time the elders are directed not to harass someone is if there's some legal aspect to it and they're trying to avoid liability or if someone's claimed that they'll commit suicide if the elders keep calling (which, I guess, really goes back to the legal liability thing). Since you're trying to get reinstated they're very likely to keep dropping by to see if they can get any dirt on you - they'll want to make sure that you're not still doing whatever you got DFed for, and they're not super likely to just take your word for it. Also, the memorial is coming up and lately it seems like the elders are being asked to call on DFed and inactive ones in preparation for the memorial/conventions/CO.
The unannounced call by 2 elders is the rule, not the exception. In most cases asking them to call before coming does not yield any results.