Do they not need permission from the nearly 500 contributors to do this?
Or, the other way (although I can't guarantee that this is true) would be to choose a compatible license with the one they were using before. Compatible license scenario basically means that the license changes are small enough so that they don't have to request from people to agree with the change.
https://www.irs.gov/Charities-&-Non-Profits/Charitable-Organ...
Many proponents of copyright assignment to for-profit corporations have argued that "it's just the same thing as what the FSF does, so it's fine", but their legal nonprofit status makes it a substantial difference.
A better argument against the FSF's copyright assignment practice is that it is bureaucratic overhead for somewhat questionable benefit.