I've published a few papers (and have worked closely with Elsevier in a business context). When we published in a paywalled journal, we had the option of paying an APC [0] to make the particular article open access. So in that sense, we were not 'required' to relinquish copyright. It was just costly to retain it.
I suspect this is how some publishers argue that their contracts do not violate these maxims, because an APC option is fairly common, even at Elsevier, I think. Many journals also permit authors to post pre-edited versions of their papers on their personal websites.
I also think that, in line with what a commenter below, a large organization like MIT is not a coherent actor. There are political battles and compromises we don't see. So publishing this list could be someone's tactic for winning the internal struggle against negotiating with Elsevier.
Chris Bourg, who is a prominent advocate for open access at MIT, is my best bet for the driving force behind this: