Are you saying that shuttle astronauts have seen these phenomena and are keeping mum in public?
One of them somewhat openly speaks about it. I think he's on record at the DISCOVERY PROJECT website.
They don't keep that mum really, at least in certain settings... like talking to an old friend or relative over many beers. But you aren't going to have many get in front of cameras saying much about the topic. These are agressive, ambitious and loyal people. They aren't gong to rock the boat for many reasons.