I once worked for an adtech company that had profit sharing instead of RSUs. The early employees were compensated very well because it was unsurprisingly very profitable. I joined after they raised money so they switched to "phantom equity" in a LLC instead of RSUs. When they went public I was granted 1 stock for every piece of phantom equity plus about $5. These weren't options, I didn't have to pay anything to exercise them. Worked out to a 50% appreciation over two-ish years of working there, so not too shabby at all.

The point is there's other forms of variable compensation beside options you can give to employees of a private entity that are just as good (or even better) than options that may or may not become liquid over 7-10 years. Twitter could set up something similar to entice top performers to stay.