I can tell you from first hand experience that this is 100% correct.
For anyone that's interested...
He did it to me many years ago, without provocation, and got me banned from a forum that no longer exists.
I had been looking into possibly purchasing some of his seeds (I was young, and naive then, I know better now).
While looking for them online I came across his Riot Seeds Facebook page.
Said page had the info I was looking for, but when Matt set it up, he missed something.
He'd accidentally left an open link to his personal FB page active on the company FB page.
Knowing that we were both members of the same forum, I private messaged him, and in a very friendly manner explained what I saw.
Riot relied quickly saying he was unaware of the FB situation, and didn't want his personal stuff out there like that, so he thanked me for giving him a heads up on it.
I went to bed thinking I'd done a good deed.
When I woke up in the morning I found that had been banned from that forum.
The reason, for harassing Matt Riot, and threatening to grass him out.
I emailed the admins and was told that no less then two dozen other members had reported me for this.
I pointed out this was completely false, I had in fact done the opposite, and helped keep his info safe by alerting him.
I told them to simply read the PM I'd sent Riot and they'd see what I said to him and that he'd replied with a thank you.
They said that wasn't possible, and that with so many members upset with me, they would never allow me back on the forums.
I used a friends account to see what was going on in the forums, and that's when I learned a sad truth, that Matt Riot is a very unstable, and dangerous person.
I could not believe what I was reading and how absolutely psychotic it was.
Overnight, Riot had created dozens of brand new sock puppets accounts, all of them posting for the first time, and worrying about Matt's safety.
With posts like "Matt told me he's never going back on the internet again, because he's in hiding, fearing for his life".
I was later informed by other folks in the industry who have worked with him in the past that Matt Riot is/was a very heavy drug addict with serious mental health issues.
When he goes on a bender, or don't take his psych meds, he gets very paranoid, and delusional.
To make an apt analogy, imagine quietly pointing out to your friend that his fly is down, and he says thank you.
Then your friend walks into the next room and starts loudly telling everyone about the creep in the other room that's trying to look at his dick.
That is who Matt Riot is.