Whatever the union may or may not have done wrong, this dispute started with a very disgruntled bunch of BA employees.
Voting to strike.
They do not seem to have 'won' anything from their employer, so even if WW crushes them at this point, the matter will not have been resolved.
So (unless they simply forget that anything was ever wrong) they will still feel aggrieved.
Something of a pyyrrhic victory for WW, surely?