This is actually a pretty good idea.
Denver is probably one of the few teams in the league that might be willing to take a risk on Tony Allen, and Tony Allen might be able to platoon with Affalo to fill Dahntay Jones' shoes.
The only problem I see with this trade is that trade exceptions cant be combined with any other player in a trade, meaning we cant combine it with Brian Scalabrine's contract which will end our dreams of getting someone like Nocioni in a trade. I have a feeling Management is not willing to trade for a big contract anyways, so this trade will allow Boston to save around 5 million dollars.
Even if Tony Allen is not traded spcifically to Denver, he will probably eventually be traded to some team under the cap for a trade exception anyways, its just a matter of finding a team willing to take him on. The ideal trade would be for a trade exception and maybe a second rounder.