I don't think it's cynical at all. Unfortunately I can't provide concrete examples, but I recall many instances over the past 15 years or so reading stuff here

I don't think it's cynical at all. Unfortunately I can't provide concrete examples, but I recall many instances over the past 15 years or so reading stuff here on HN where founders/companies expressed a belief that they should be able to claw back even vested equity from employees who have left the company pre-IPO. It's super super gross, but it's unfortunately a thing. Hopefully that's not what's going on here with OP, but I wouldn't be surprised if it is. If the company is offering a sell-to-cover option to existing employees, they are certainly capable of doing so for former employees as well.