There are no shares for them to sell because it is a private entity. Their RSUs/equity would have either been deleted, converted to private equity that you can

There are no shares for them to sell because it is a private entity. Their RSUs/equity would have either been deleted, converted to private equity that you can maybe sell on the secondary markets at best, or converted to cash bonuses. I think 1/3 are pretty unlikely and 2 would have those RSUs in the gutter as well. Maybe a disgruntled Twitter employee could comment.