Narrow Runway - because your roster may have you working between 24 Dec and 26 Dec, that may be STBY or flights. easyJet operate very few flights throughout the network on Christmas Day . Historically, if you're UK based, you would more than likely be stood down from the Christmas Day STBY on 24th. With the strike dates being called on 24th and 26th there is a distinct possibility that some may spend their Christmas in LIS at short notice. Nothwithstanding any contingency plans the company may consider. Noone is talking about any easyJet crews volunteering to operate on days off.
I take your point that if you have a rostered duty, even if it be STBY on Christmas Day when there are no flights planned at your base, you still have a rostered duty and therefore Christmas Day is not your own. Nonetheless, particularly if you have young children it is going to be a significant disruption and disappointment to you and your family and this is the prospect many fear. The issue is that to be called to do a rescue flight is unfortunate but this is a deliberate choice of dates which some feel is poorly thoughtout and inappropriate as it may alienate your colleagues, others feel it will send the strongest signal to the company; the debate goes on.