first of all it's a regular experience where somebody tripping is convinced s/he's acting weird just be assured that they seem completely inconspicuous for an observer.
You have a point, obviously - but I wouldn't be surprised if mushrooms actually heighten awareness and response in animals and some people. Mushrooms tend to fog the mind only with regard to emotional responses. But other than that it seems one acts mostly pretty rational - only the perception seems to be changed. I took enough psilos and LSD to lose control of my ego and experience amnesia but from all I can say I never really acted irrational. Some tribes take psychedelics before hunting also.
Good for that person. But I'm not sure if that was "smart" to convince somebody with mental problems to drink mushroom tea at a party ... that's recipe for disaster.