No I don't think he should take away staff travel because my personal opinion is that he's punishing staff for doing something they are within legal rights to do
I guess one response to this is that, while it is legal to go on strike, there is no reason why the employer should make it an easy choice and not do all it can, legally, to mitigate the damage. If removing staff travel might put some people off actually striking, both now and in the future, I don't really see why the company can't do it.
One legal action by strikers has led to an equally legal response by BA.