So you plan to force me into accepting your position if I don't take it when you ask nicely? I'd say you're already not polite.

You already exist in a democratic system (assuming you're posting from the first world) where majority (mostly, some caveats) rules. This isn't any different. Everyone gets a vote, not everyone gets their way.

Not quite. I live in a republic. The majority wins elections but still don't get to totally trample on the minority, because we have a limited government.

Now, a union election isn't a government election, so that doesn't totally apply. But, for example, the majority has decided to pass legislation that makes my current state a right-to-work state, so a union can't require me to be a member, even if they win the election.

Of course, unions could campaign to change that law. But that's a different set of elections they'd have to win...

Is it at all possible, in any scenario, that people might have other reasons than purely personal comfort for sitting out a particular push for change?

It is possible, and I am receptive to enumeration of those reasons. One must be able to entertain both sides of an argument. Selfishly, it would help me strengthen my own argument.