I was closely involved with the negotiations of an ALPA regional carrier a few years ago.
Haven't heard for sure, but I'd bet good money that ALPA national wanted the Comair pilots to accept the mediated offer.
In my old carrier's case, ALPA national wanted us to settle for much less than we finally got - after voting down Maggie Jacobsen's "compromise" (contrary to news reports, this is not the first time she has offered a NMB-written compromise contract).
Randy Babbitt personally told me we were asking for too much. This was for a contract with a top RJ rate of $65 / hour!
What is happening at Comair is being driven by the Comair pilots, with their MEC in the lead, and line pilots following in full support. ALPA national is probably just paying the lawyer bills and praying for it all to be over.