I think it is pretty clear (at least, again, from the transcription) that he expected to have more involvement in writing. Seems that JP did the drum parts for ADToE and TA, which MM then laid down. So I can see MM wanting that to stop so he can be an integral part of the recording/writing. And if that is indeed the case, I don't blame him for that.
Well, it's not really like that. For ADTOE, MM said that JP gave him basic programmed drum tracks, nut he could play whatever he wanted inside that, let's call it, template. For TA, he also came up with the drum parts he wanted to play, even though he was probably given the indication to play some parts simpler to let the melodies and the story itself be the main focus. He's not, tet's say, disappointed for not being able to write the drum lines he wants to, but for not being able to contribute his own musical ideas (riffs, harmonies, patterns, sections, progressions, etc) to the band. He's very capable of writing songs by himself (he's said that many times) and that's why he's putting together a new solo album. He wants to contribute with more than just drum lines.
Hate to quote him on something like this, mainly because he uses it to justify his arguments on how he was also one of the main writers for DT, but, as Mike Portnoy has said many times: writing for the song isn't the same as writing your drum/bass/keys/guitar/whatever parts to a song. You don't get songwriting credit for that.
EDIT: I was writing all this and Bosk came, summarized it, and posted it faster than me