Hello John,
welcome to the Moon.
I am 21 and as a representative of youngsters here there is only one possible comment on your accussations of lack of open mind on Aural Moon. This comment is mega-ROTFL!
I agree that there is lot of nostalgia here, many Moonies look for the spirit of the times they were growing up in but for God's sake it's not the whole AM style. It's essence is the mix of generations, mix of spirits. That's why middle aged Moonies enjoy also Porcupine Tree, thats why I enjoy when for ex. Wishbone Ash is played. THAT is the Aural Moon.
Now strictly about DT. Again I agree with you. DT is pure prog, they are evolving but always in progressive style, every album is a bit different but Portnoy cares about the progressiveness. I consider latest release Octavarium as a perfect release for the Moon, because of it's classic prog ROCK (not metal) feel. Especially title epic, with echoes of Hackett, IQ, Neal Morse, with the beginning as in Floyd's Wish You Were Here.
BUT
We are small community, that's why we don't have to be 'politically correct' in aspect of playing what we should, what's most popular etc, so personal tastes are clue factors of what is played here. Taking that into consideration I fully constent to decisions connected with personal tastes of AM bosses because even if I don't share this point of view in given situation (and as I said I consider DT prog) they are doing such a marvellous work here that such matters are absolutely 'excusable'. So I'd like Octavarium here but if it's not I'll request sth different and thank AM crew for their great work.
BTW. I see grain of truth in the arguments against DT on AM because of their show-offish way of playing. It irritates me too (I don't like Awake). But they have quite many compositions in which there is great, 'tempered' progressive rock. I highly reccommend Octavarium as a release for the Moon (maybe apart form opening track

).
So to sum up, you wanted to provoke. Miss. As we here say the bullet is in fence.