From what reporting I’ve heard, it’s an informal poll. If I had to guess, probably some google form that was emailed out to members. Given the leadership of the union spoke at RNC and praised Trump, I wouldn’t read too much into it.
That said, still very possible uneducated, mostly male members support Trump for personal reasons, and honestly I don’t know how much that should matter. The endorsement actually should reflect whatever candidate has the unions interest in mind, which is why most other unions are supporting the obvious, pro-union candidate.
To get the kids to bed and start up a video game. That’s all. That’s all it takes for me now a days.