Good, I've been curious about how the date is set (I have a bunch of backburner projects that's been drafts for ages) and this answers my questions about it. I agree that projects' publish date being set when they're restricted-access might not be the best rule, since this will just hurt projects that are legitimately trying to polish and test their stuff properly... it's better to base it on when the project first goes public.
Maybe having a page where you can browse "recent devlogs" could fill the purpose of having a 'recently changed' category for games while being slightly harder to game as a system? (since it's hopefully relatively easy for people to see when someone posts shallow devlogs with no real value, especially if they do it constantly, while you lose that nuance if you'd sort games based on when a file or page was last changed... it's a much more incremental thing that's harder to judge). Just my 2 cents.