I don't think this is quite as controversial as some are making it out. Many decades ago I was introduced to this by a large telco that I worked for, who took us all in for brainwashing or cultural enrichment or whatever those butcher paper sessions are. I remember we were told to always break bad news in a sandwich - make a positive statement first, break the bad news, then follow it up with a positive statement.
I summarily noted and filed that information, I'm not sure it rubbed off on me but I do remember the lesson so it did have some impact on me. It's not telling people to lie, it's just telling people to consider how to deliver bad news. You can imagine that answering "no" to someone isn't considered the most customer friendly approach. I dare say said union rep is playing up the issue somewhat for the benefit of their client.