Absolutely agree. Mr Walsh does not make the law. If you are sick, you are sick.
This is right in one respect: WW does not make the law.
However, the law never seems to be as clear as it might be.
For instance, BA will know (since they collect data on almost everything) how many cabin crew, on average, go sick on any particular day. Say, for day 1 of the strike the number was 50. Suppose that, on day 1 of the strike 700 people went sick. 700 when normally there are 50.
BA might then be able to argue, in court, that this represents unofficial industrial action - clearly these people can not all be sick as look - we have data going back X years to show an average of 50 people go sick, it's never more than - say - 65, never fewer than - say -40. Not only might you be considered on strike but you might not have the legal protections of the legal ballot - because BA are saying your actions are unofficial.
Your lawyer will presumably argue "look my client has a doctor's note saying he had blocked ears" or whatever.
Who knows which way a judge will go. Would you be willing to take the chance? I don't think it's as clear as people might think.
What would you say if, despite your doctor's note, the judge said "look BA weren't asking you to fly - they made that clear - they were asking you to report at CRC - they are two different things and blocked ears don't prevent you getting in a car and driving in. Therefore, given that you acted unreasonably once I am willing to take BA's interpretation of events and assume you have acted unreasonably twice."
BA can then dismiss you for breach of contract. Oops.