Not trying to be dismissive but it is a band playing another band's songs so not sure how you can call this anything but a covers band. OK it has one former member of that band (the drummer, not the singer or even one of the soloists) who was the mastermind of the songs lyrically but he has put together a band to do cover versions of the songs live. Transatlantic and LTE were side projects playing original material, this is not that. If this turned into a real side project playing new material then I would be very interested to hear what they came up with as they are talented guys.
I'm sure Mike would like to see this as something like Roger Waters going out playing Pink Floyd stuff with a new band or even Mark Knopfler playing Dire Straits stuff but Mike was not Roger Waters or Mark Knopfler in Dream Theater. He was more than "just" the drummer clearly but he was not the voice of the DT nor did he write the huge majority of the songs on his own.
Again, I have no problem with him doing it and hope the shows go well as these songs mean a lot to him and I'm sure to some others who've been through similar experiences with drug and alcohol abuse. It's just not something I'd want to see live, even if it was the real band playing the songs, and it makes it easier to say no when it is not DT themselves.