I am not so sure an airline can remove staff travel privileges from a striker as long as the industrial action is legal.
One strike in a different company resulted in the airline giving everybody who went to work a free flight to a destination of their choice as a thank you.
The union waited for some of the tickets to have been used and then challenged this in court claiming "discrimination". The court decided in favour of the union and all strikers had to be given the same, a free flight.