If you(singular) strikes you lose benefits.BA Don't care you are a striker.WIN
If you(majority)strike then every one loses.Onus on the crew to return a no vote.Battle fought amongst crew.WIN
It is a very well thought out plan.
Obviously, the latest email won't be the last of the comms. What BA are trying to prevent at the moment is a "Yes" vote. If they succeed, BASSA will be dismantled by Easter. If they fail and there is a "No" vote, they will attempt to dissuade potential strikers from walking.
No doubt Lurker will get suitable clarification of the email at that point.