Like many well-intentioned regulations, I worry that the new focus on denying (gun) rights to the mentally ill will have precisely the perverse effect you predict, valnar.
If I were going to do one thing to reduce the number of mass shootings, I would offer parents of young, bright, but very troubled young men some form of mental health assistance that does NOT threaten to ruin their child's life. Right now, the choice is between seeking committment, which ruins the future for the (adult) child, and doing nothing, which risks terrible and insane outbursts of violence. Making the former choice MORE punitive doesn't fix the bad dynamic.