Confusing. I’ll be interested to see this explained to mortals.
But I would assume that derived works could not choose to use the code as BSD - it’s not “choice of copyleft or BSD” it’s “copyleft unless you try to do something shady.”
Somehow..?
But is that true? Basically, the license is copyleft now, but if certain conditions occur in the future, it will become BSD-like (let's go with that designation for familiarity).
Thus, the license is effectively (copyleft | BSD).
A project which uses regular old predatory copyleft can therefore use it now and continue to use it, whichever way it plays out.