Actually I am wondering why the mother allowed her crazy son access to her guns.
All the wondering starts and stops right there.
I agree with you. If I had a crazy kid, as in this kind of crazy, the last thing on Earth I’d be doing is teaching him (or her) how to use a firearm.
I had a somewhat crazy friend crash on my couch for a few days several years ago, and I made damned sure I hid all the guns and locked them up. No easy feat....she showed up on my doorstep one evening! I told her she stank, and needed a shower, so when she was in the shower, I used that opportunity.