If they had already been paid out, yes. Company bought you a $10k car in January, you strike in March. The company isn’t allowed to retroactively “unbuy” the car and declare that you now owe them $10k. Even if the condition for keeping the car was a full year’s employment you can’t take it — striking isn’t legally quitting.

Even stronger, if employees usually get an annual bonus but the year of the strike they don’t you might get bitten for retaliation.

I feel like yes, you would get options in your contract. But it doesn’t matter. The legality of this isn’t why it’s stupid. It’s the immense bad will from a class of poor students that are already doing a ton of work for very little. They would effectively now be asking students to pay to work.

Organized labor is coming for grad students.

If you had been issued options to buy shares that had already vested it'd be pretty insane for a company to try and claw those back. Pausing the vesting schedule might be a bit more understandable but is honestly pretty damn petty for what you're getting unless the strike lasted a good chunk of the year.