^ Theoretically there is room for interpretation. None of the heroes on Earth prime know about the continued existence of parallel Earths in this new reality. They still think Oliver put them all on one Earth.
At the moment, sure, but I don't think they plan to keep that up forever. I wouldn't be surprised if they rediscovered the Multiverse by the end of the season (however delayed that might turn out to be), even if it remains difficult to access.
I mean, given that Stargirl is being promoted more as a CW show than a DC Universe show, I'd be surprised if they didn't cross it over with the Arrowverse eventually. And it seems to me there must be a reason why they chose to designate its universe as Earth-2, despite there already being a previous one, rather than some other random number. It implies they intend it to be the primary "other" universe, which suggests they plan to do crossovers.
If so, it's kind of interesting. Look where we're going now: We have Earth-Prime with what's essentially the Justice League (though they haven't used the name yet), and now we'll have an Earth-2 with the Justice Society, and if I'm right, the two may have periodic crossovers. Which would mean that the post-Crisis Arrowverse would end up recreating the status quo of the pre-Crisis comics -- the very status quo that Crisis was created to undo! How ironic that would be.