I think it, indeed. IMO the reason that Universal didn't contest the first sale doctrine is because they don't want to be the test case for the whole industry. Challenging the first sale doctrine (which excludes music but not movies) is the nuclear option. I believe it would succeed, as the arguments for the muscal exception are substially the same as those which would apply to film, but this strategy is not without risk: were they to bring such a case and lose, the entire film industry would be saddled with the results and have to rebuild their distribution models from a lesser position (to say nothing of their reputation as 'bad guys').
Acting through the distributors is a feint, which Universal is big enough to attempt (in that they have sufficient influnece with distributors) but which doesn't cost them too much if they lose. Note that they haven't lost yet - The court has dsimissed some of Redbox's claims, but affirmed their right to bring a case asserting antitrust behavior by Universal.
Whether they'll win it or not I don't know, although the judge seems sympathetic to Universal in their distributors voluntarily entered into an agreement with the studio to distinguish between DVDs sold for retail and for rental, and Universal are just asking them to stick by that contract, which predates any agreement between those distributors and Redbox.
I don't know the specific strategic thinking of Universal's lawyers and here, and as I said I'm not a lawyer myself - this is just my reading of what's taking place. I can say that the distribution executives that I have spoken to about this all hate RedBox - while admiring their chutzpah and business drive, they loathe seeing their product dispensed and priced like a bag of potato chips.
Thanks for reposting that opinion, BTW. I'd forgotten how many jokes it contains :-)