As usual, the issue is conflated and polarized. Agenda driven journalism.

The old rule put in place by Obama required the Social Security Aministration to report to the national background check system people on full mental disability benefits, including veterans with PTSD. In fact, the State of California started going around sending police SWAT teams to residences of registered gun owning veterans with PTSD who were then flagged on the FBI's background check system . 

Obama's law also reinforced the stereotype that people with mental illnesses are violent, which is not true in the vast number of cases, according to the ACLU, that objected to Obama's law; in fact, people with mental illnesses are more likely to be victims of violence. The new law does not totally eliminate the restriction: only reduces the number of illnesses under which the ban applies, by not automatically disqualifying those on full social disability benefits. The latter included those with eating disorders.