A7X has been nothing but classy. To be honest, when the truth is given straight, I find that more classy than dancing around the truth. When MP left A7X, I liked that M Shadows was honest and said, hey look, MP was too 'press release' happy, we don't do that in A7X. We keep to ourselves and go on. When it comes down to it, MP uses social networking to let his mind loose and basically say what he's feeling. This current period in his life ain't exactly the best time to speak your mind on the internet. I understand how A7X felt.
Another thing that I understand is that A7X didn't want to become: Mike Portnoy and Avenged Sevenfold. Quite frankly, that very well could have happened. I know that once that new A7X track was released earlier this year, I saw a few people on MP's site say: Yeah, since Mike left A7X, I don't listen to/like them anymore. No doubt that some people only started listening to A7X because of MP. If I was in A7X, I certainly wouldn't want to have my band surrounding one member and having his name and then my band name.
Another point too is exactly what skydivingninja just said. A7X wasn't prepared to keep MP full time. They brought him in as a touring member for 2010, I don't think they ever had it in their mind that they wanted him full time. After Jimmy died, they said between themselves that they wanted an up and coming, young drummer to come into the band. They just wanted MP to get them through the beginning of the tour.
Also, the age difference and personality differences.....