MM has always been gracious to MP and has treated him with respect.
When Mangini won the audition, I remember him saying something like:
"Please know that I am not trying to replace Mike Portnoy, or anything he has done for this band. He is a good friend, I love Mike. He is the only drummer who ever came up to me and told me how highly he thinks of me." (Not an exact quote, only what I can remember)
I could not find the clip, but it was similar to that. This tells us that MM has a ton of respect for MP, and they've been good friends in the past.
I certainly hope this new interview is not accurate.
As everyone has said, it would be very unlike MM to call Portnoy "controlling", hint that he is a "control freak", and say that they would not have received a Grammy nomination if MP was still aboard.
If it is indeed fake, I also hope that someone brings it to MM's attention, so he can clear things up with MP before he reads it for himself.