If sacked under an "unprotected" strike, and treated the same as other strikers, there is no recourse to an ET, no compensation payable.
With due respect - this is rubbish. There is always recourse to an ET. It may well be futile but if sacked an employee can always dispute it.
The only thing protection provides is a guarantee that the dismissal will automatically be deemed unfair. That means compensation will have to be paid. Being sacked during an unprotected strike can still be unfair, it just means the dismissed person would need to prove the lack of fairness at the Tribunal.