maybe not an idiot, but clearly out of his scope or depth of knowledge.I don't know if I would go as far as calling him an idiot. Using a device to disable the VCM does sound like snake oil to many.
In this case I would take the fresh fluid as maybe the fix. All these newbies must realize that, just because they did get the trans TSB, that does not mean that the fluid does not still need to be regularly changed. The factory service interval is every 30k. That is a minimum. If you want to keep your van long term, change it every 15k. It is quite possible that the pressure switch gets gummed up with bad fluid. I would not be paying to have it changed unless it was happening repeatedly with fresh fluid. If it is really an issue, it will be back.