I wonder if there's any possibility that the staff members are under NDAs or something, and thus can't really say anything. Mostly I'm considering this due to the recent interest with King's Quest, not only from the 2015 game by The Odd Gentlemen, but also the hint from Microsoft that they'd possibly like to see something done with the franchise.
The only other thing that makes any sense to me is that they don't want to show progress with episode 5 until they're absolutely certain that they can see it through to completion. That's more or less what was said in the last video update at the end of 2017 (which I know was before the news post in 2019 promising more updates, but still).
Admittedly, I didn't enjoy TSL too much when I played it some years back (although I really should play it again to see if my opinion has changed), but I'd still like to see the project completed, especially when it's this close to the end.
