The guy was a TROP convert, just about guarantee it.
What is a TROP convert?
I thought so, too, after I read the description of his outfit. But so far it doesn’t seem that any hard evidence has appeared.
Islam is so bizarre that it attracts the mentally ill or losers with an imagined grudge against society. It makes them feel powerful and makes them feel that their grudge is somehow affirmed and gives them the right to attack. I think Mormonism, in its early days, may once have done so, but I don’t think it does so anymore.
If he was Muslim or regarded himself as Muslim, I doubt that we’ll ever know about it. In any case, I think Mormonism was just a step on his journey away from the Christianity of his youth (and pre-psychotic days).