Re: overmentalizing
From a campaign perspective, I had a hard look at this the last time I ran Champions. Mine was a 'high-realism' game which took a hard look at how supers and their powers would interact with normals in the real world. And it looks to me like your problem-player is approaching your campaign from that angle, at odds with you and the rest of your group.
What I did was assume that organized crime (and crime in general) had already been subject to the kind of treatment from mentalists that you're describing -- after all, the supers had been been around for a few decades. The end result was that the surviving criminal organizations had recruited their own villainous mentalists, or were run by mentalists. The biggest, baddest organization recruited lots of mentalists (and other supers), who promptly took over the whole thing for themselves.
I'd suggest a solution like this for your campaign -- have one of the criminal organizations recruit a mentalist (or several) to help protect their people from mental intrusion. Later, the mentalist villains might even take over the organization, and give the PC's some real trouble. It worked pretty well in my campaign.