Dude, I'm as anti-Rossi as anyone, but you honestly can't imagine a scenario where they just thought it would go away if they gave the impression that they investigated, half-assed it. I think most people here were giving them the benefit of the doubt during the "investigation" time and being respectful by not contacting them. Heck, SaraB only forwarded them the summary spreadsheet after I suggested here on this thread that we shouldn't assume they are taking it as seriously, or looking as thoroughly, as we were here. (probably a mistake in hindsight... should have bombed them & put the pressure on them in those first several weeks). It is very possible that in that month they were "investigating", Mike Rossi, via the scare tactic of working with a lawyer, was the squeaky wheel. Finally, human nature is to want to appear consistent, and not look stupid... so once they issued their decision, they will be reluctant to change it on a whim.
That, and as some other RDs showed in the Kip Litton saga, for whatever reason some RDs are very reluctant to DQ a participant, even when the evidence is overwhelming. For god sake, Kip Litton had multiple DQs lining up one after another and even then some RDs didn't DQ him. They weren't doing Kip a favor or covering up something.
For you to say "it simply makes no sense" is incorrect. For some reason, you can't imagine it or understand it, but it makes perfect sense to me. That's why I initially encouraged at least one person to make contact & share the info we'd researched here.
One good rule to live by is to never assume malice when incompetence will suffice.