Firstly (and unequivocally) I hope that Captain Tom Moore is soon out of hospital and on the way to recovery and vaccination.
I am, though, very disappointed by his family jetting off to the sun during some of the darkest days of the pandemic. Regardless of the precise legality of the trip, it is bound to have given a (possibly spurious) validation to so many other people indulging in the widespread cult of 'just how far can I bend these rules'.
As a public figure, and the family of such a figure, there is more to consider than simply whether the trip is legal (or indeed advisable for a 100 year old) - the effect on the behaviour and morale of others needs to be considered.