Usually late stage startups switch from options to double-trigger RSUs years before they go public. I doubt anyone at Uber has unvested stock options.

Assuming anyone laid off had unexercised options, they'll likely have a short window to exercise them before they expire.

Furthermore, Uber is a public company now, and there is (as far as I know) no outstanding lockout period for employees. IF anyone has outstanding options, that are subject to a (most likely) 90-day exercise window, they can be exercised and immediately sold.

The typical "exercising of an option for an illiquid asset which will be taxed as if it's liquid" problems with start-up stock options simply don't exist in this case.