The first thing you need to do is read your insurance policy and then call them and have it all explained!!! Diastasis rectis is not covered by insurance. HOWEVER, the hernia would be. What I think the PS's might be telling you is that while the hernia would be covered, the diastasis rectis AND the TT would not. However, with a hernia, much of the time a panniculectomy IS covered, which is removal of the redundant skin. Sounds like a bunch of insurance hooey, huh???
I had severe diastasis rectis as well, and while it should be considered medical, apparently it's not. Go figure.
Definitely get to your insurance company and talk to them, and then you might want to go to a surgeon that has some experience with WLS patients. I think that might be helpful.