Quite plausible...
I agree that the Noachian is the most interesting time on Mars, but almost the most inaccessible. We need to work back to it through a fog of geology and impacts which, IMHO, is not helped by the rabid insistence on a post-Noachian Blue Mars.
However, setting that aside, your scenario for the Noachian is certainly possible and possibly plausible. I don't want to crystallise on it yet, though, since I think we need a bit more work on CO2 condensation and ephemeral atmospheres.
If they hadn't got this damned 2 abstract limit I'd raise the issue at LPSC, but this year I have more important fish to fry.