The airlines I quoted above, certainly at the time, would only take you as an FO anyway - as do NetJets.
However, I would think that you are probably correct with regard to operators that do take DECs although that is always going to depend on the market. Still that is there loss. A few years back I had dinner with a guy that had flown Concord with a "five-star" airline when he had just joined us. His Line Trainer was also there and this guy said that his Line Trainer had made more decisions in that week than he had made in 15 years flying Concord. I think many airlines miss the point in their recruitment strategy. Teaching someone to fly particular type of aircraft is not really that difficult – teaching them to be good Captains is a lot harder.