Airlines having to pay EU compensation in case of strike action is a double-edged sword. It will certainly hurt LCCs most as they have to pay out a lot more than they got for the tickets, but it might also allow airlines to claim this as damages from unions in jurisdictions entertaining such claims. It is also not in line with the principle of compensation that are meant not to apply if delays/cancellations are caused by events outside the airlines's control (which seems to apply to a strike).
All the best to the RYR pilots nevertheless.