Which is yet another example of why I have such disdain for SAG. It's not like we're talking about a situation where the studio was really trying to avoid hiring union members. We're talking about some producers trying to do something nice for a group of extremely loyal and dedicated fans for one day.
From the POV of the fans, perhaps. Any time management violates a union or guild agreement they have a reason that sounds good to someone. The job of a union is to protect the rights of workers under the negotiated contract, not applaud while the bosses pull a publicity stunt that takes work away from their members - if the union can't or doesn't do that every time, then they're not good for much.
I read that the ST:TMP event led directly to a change in the studio/guild agreements to prevent it being pulled again, and that's all to the good. It's dandy for people who don't have an honest stake in the outcome of these things to view the process of sausage-making with "disdain" but I'm glad the guilds are there and doing what they do.