The fundamental question to answer with specifics IF all the weapons were traced back to a FFL is WHO filled out the Form 4473 for the purchase? Were any or all of them gifted to the son (there is a Form 4473 stipulation for this)?
This article doesn’t discuss that, and it is entirely possible that the mother was the one that purchased them. If so, she is open to liability if she allowed her son free access to them - especially if she had provable cause for concern over his behavioral state.
I ‘gifted’ some firearms to my daughter and my son-in-law. The first thing I required both of them to do was to obtain a weapons carry license and to take a basic handgun training course (classroom and range). Due diligence.
“This article doesn’t discuss that, and it is entirely possible that the mother was the one that purchased them.”
The media generally avoids putting women in a bad light and/or highlighting when a female engages in wrongdoing or is responsible for a tragedy. Many times the names and pictures are withheld, and no interviews conducted.
The msm behaves similarly with muslims and minorities unless it is somehow in their interest to do so.
I think most people know why this is.