This is my first post. It would have been simpler if TFM just posted some email that you can contact such as gmail, yahoo and so on.
He might have done so without me understanding.

I created a matrix account and then immediately deactivated it after reading his security warning. Then I clicked on the link
https://merovingian.club/web/@Tfmonkey

And selected sign up

I just used a normal email address I use for other things. I do not know if that was a security risk and there was a middle step I skipped