Why would Chicago do this? If the intent is to retain and trade dadonov at the TDL, that's going to be pretty difficult with only 3 retention slots and Kane and Toews taking up 2. Domi and AA were signed as well to trade at the TDL.

Hoffman is a defensive black hole. So bad, that despite being a sniper, when his line is on the ice going back to Ottawa, the other teams scores more then his line.

Isn't the idea to tank for Bedard? Hoffman would be perfect to help that. That said Chicago shouldn't do that, Arizona could entertain that offer.

Chicago says no, I'm not sure how many years Hoffman has left on his contract, but I know it's more than 1. Hawks are adding $10M in cap space for garbage. Easy pass.

Chicago says no because they're in a rebuild.
Arizona says yes because why would Montreal do this...

your title says, "Why wait for TDL?"
The answer is in the value obtained by those players.
Dadonov is not a bad player if you look at his stats; he had a medium season last year and still put up 20G 23A for 43 pts.
At the trade deadline, Dadonov alone will fetch a 2nd round pick, as many believe.
That's a good reason to keep him on board; Habs are in no rush.