If you can prove the firing reason was this. Which would be rather hard to establish unless he somehow gets his hands on some email from the top management saying "that bastard joined a union?! Fire him on the spot!". I estimate chances of that as fairly low.
Why would you estimate the chance as being low? Are you unaware that Google has a history of legally questionable anti-union activity? Never heard of Project Vivian? Of the case they had to settle when they fired six union organizers? Is anything less than absolute legal certainty a low chance?
Each case is decided on its own merits. If Google fired union organizers - which, since they settled, is not even a legally established fact (that's likely why they settled, to avoid having any facts to become legally established) - that doesn't mean they fired this particular person because of it. There are thousands of people in that union, which weren't fired - and that's what the opposing attorney would point out the first thing. And you'd need to establish some causal link between union membership and firing - with actually legally acceptable proof. Getting such proof is what I think of as "low chance". Separately, I also don't think joining a really toothless union would be the cause for firing - unlike the other things described in the article, which most likely were the real cause.
Yea I would imagine that must have factored in. Not at all saying that they should have of course - the opposite - but it seems odd they did not also mention that a bit more.....
