He may be a member, but he would not accept an official position or engage in picketing or otherwise agitating for the cause of a strike
As far as I know this is still the official position in Canada. In the event of a strike you would not cross a picket line (scab) but you would not be ON the picket line either. If you are not on the picket line the union will not pay you strike pay but there are no other sanctions involved.
I decided to support my union the last time we were on strike and walk the picket line. It felt good. No elder ever questioned me about it either and that felt even better.
Yet, if my memory serves me correctly, JWs are no strangers to political activism. I believe they demonstrated en masse in NYC to get one of their pet Brooklyn Heights construction projects approved (then-mayor Ed Koch is reported to have said ``look down there at those people; not a vote among them"). And also in France, to protest the tax ruling.
When they have their interests at stake then any and all protests are O.K. What the HELL ever happened to the old "wait on jehovah" BS