Why Are Unions Not Supporting NFL Ref's?

This weekend is labor day and without a doubt, the biggest labor confrontation is between the NFL and it's referees.
Other than the NFL player's union, no other unions have supported the NFL officials.  No union has threatened to not work for NFL stadiums out of support for the officials. On the web sites of the major of the major unions I read, they have not had any signs of support for the NFL officials.  This is kind of surprising considering the NFL is using replacement officials, or in union speak- scabs and the issue is well known among NFL fans.
So, why haven't the various unions shown support for the NFL officials?  I honestly don't know, unless the officials are considered to be too much 1%ers to gain union support.
So, I guess, unions are just there to screw workers, steal their wages and not support their brother unions.
Yeah, happy Labor Day to scab unions.