Interesting to note that the commercial off-Bway runs of LITTLE SHOP and TITANIQUE are also talking of unionizing, per the article.
It can be a tricky conversation when it comes to off-Broadway & regional unionization, because you also have people in key administrative roles making like...$40K a year for 40+ hour weeks. (Some do get healthcare and other benefits of salary, though.) So if the stagehands & production staff want to unionize, I do think their whole staffs should be talking about doing it too, though would obviously not be the same unions.
With commercial Off-Bway runs, sometimes non-union houses are chosen specifically because they don't have union overhead. And that can be a reason not to do a show.