They are saying that he was taking Ambien, anti depressants ( SSRI ?), anti anxiety meds (Xanax).
All of these have been linked to bizarre, violent behavior.
PTSD has been put to rest as he never saw combat.
Normal people, married with kids, don't just start shooting people in a cold, calculating way because they feel wronged or slighted which is why I'm leaving Sudden Jihadi Syndrome in the mix.
The reason that I mention hassan is that it was a similar crime, carried out in a similar fashion on the same base. To this day the administration still denies that it was terrorism and labels it "workplace violence".
There is no statistical evidence that mentally ill people on SSRIs are more violent than mentally ill people who are not on SSRIs.
There is zero evidence that either Ambien or Xanax makes people violent.
I agree that normal people do not just murder people in cold blood for perceived slights.
Ivan Lopez was not normal.
He pretended to have a medical condition he did not have - as you correctly pointed out. Normal people do not do this.
Not only did he claim PTSD, he also claimed to have a TBI for which there is no record.
His social media footprint indicates his morbid tastes, but does not indicate that Islam was one of those tastes.
Let's be rational and apply Occam's Razor.
There is no evidence that he was interested in Islam. There is plenty of evidence that he was a nutjob.