Management does not "reward" pilots by buying new airplanes. They buy and aquire new aircraft in order to increase their revenues and profits, the more aircraft flying, the more money an airline makes (as long as there is demand for them). Delta has determined the demand and need for more regional jets, namely 70-seaters. They have already inked a deal with CHQ, allowing CHQ to operate 16 EMB 170's. These aircraft are to be put into service slowly over the next 2 years. This is all that CHQ can afford and logistically put into service. Also, there is a limit to how much flying can be flown for Delta because of their other airline affiliations. In other words, CHQ will not be getting any more jets for Delta for a while. Also, ASA has already got their allotment of orders and logistically cannot receive more at the present time. That leaves Comair. Delta needs Comair to operate more jets, and they will get them.
Comair can aquire new aircraft and will make a nice profit on each one they operate, no matter that the pilots make a little more than others. However, Delta/Comair have been trying to lower their labor costs for a long time, in order to make even more profit. Lowering the labor costs at Comair will, in turn, lower their labor costs at ASA and allow them to demand cheaper contracts from other airline partners.
A deal between Delta and Comair has probably been already made, just not made publicly, although Embraer's stock has already gone up due to an imminent order from Delta/Comair. But, before officially making this deal, they figure why not try to get concessions from the pilots (and FA's) first. They figure pilots will think in order to get new airplanes, they must lower their pay; in other words, fool them. Delta/Comair will get concessions, the planes will come, and everybody will be happy. This way Delta/Comair can kill two birds with one stone: They get new airplanes to increase their revenue, and get a lower labor cost structure from Comair and all their airline partners.
You state that companies don't sit idle, they grow. You're right, and Comair will grow because they are a critical part of Delta's system. Comair has had the highest paid pilots for a long time now, and has been receiving new aircraft and making a nice profit. Currently, they have no aircraft on order, and everyone else does, so logically it is Comair's turn. Delta wants more regional jets and needs Comair to fly them, thus they will get them. Delta is not going to just never allot more aircraft to Comair and allow them to stagnate and not be as profitable as they can be.
Don't you find it strange that Comair already has developed an exact timetable to get new jets? Bottom line, Comair is slated for new jets, and will get them in order to remain profitable to Delta, and they are just using this need for jets and have developed a timetable to trick Comair pilots into thinking they must take concessions in order to actually get them.