As a half-winger, is there a risk in joining our IBT brothers and sisters on the picket line in uniform?
Nice thought but I wouldn't suggest it. I don't think you'd be terminated for it but you now have flight office notoriety. You don't want that on probation.
The fact that you're having to ask the question is your answer. Absolutely not, under any circumstances. Show up, do your job. Be a good employee. Once your year is over, feel free to engage in union activities.