If the HUB has seven or eight restaurants as Alicia mentioned on the podcast, then I don't see how it makes any economical sense to design it strictly for theme park guests and close it early. (Keep in mind that each land also has a place to eat or two, so that's 12+ restaurants.)
I don't see what the big issue with logistics is. There's a bunch of ways this (open night HUB) could work logistically. Here's how I would do it:
Park entrance lines are pretty much dead later in the day, with only a few lanes open. So, it would be reasonable (and not a cluster F) to ticket guests at the entrance to each land after a certain hour, let's say 6pm on most days. This would keep ticketed guests inside those lands for the last park hours, and it opens the rest of the HUB to other guests.
Keep in mind that the logistics of this is actually very similar to how they close the current parks every night, where they close the entrance to certain lands (like Diagon) but allow people who are already inside those lands to finish what they were doing (like riding Gingrotts).
The logistics here are also far less complicated than HHN (and specifically Stay and Scream). It's something Universal has experience with already. None of this requires any advanced technology (eg facial recognition).
Side note on facial recognition... Everyone should know that facial recognition is not required for the open HUB concept. However, Universal has not stopped looking (keyword looking) at the feasibility of facial recognition for Orlando (as of a few month ago). IMO, it couldn't come sooner. Fingerprint scans are flat out disgusting, and should be seen as such, especially in a time of a pandemic.