If i recall the last time an astronaut claimed to have witnessed aliens, it was just urine floating in space after being ejected from their own craft. This all just reminds me of the Aurora Project fiasco. Some astronauts have seen wierd stuff, but things arent always what they appear to be, and our brains are wired to jump to conclusions.
To be honest though, i didnt have a clue who this man was until he hit the headlines with this. Perhaps this is a grab for attention , perhaps not. Anecdotal evidence is not evidence, nor is his opinion. Anything he has had to say has all been here-say from the looks of it. His reputation doesnt count for anything, hes a human with an imagination. He is a complex organism capable of complex fault as well as achievement.
There are depts that track UFOs ( i mean cmon, an unidentified flying object is of military interest), it doesnt mean we have little green men. Saying we have little green men seems like something that is said to spark the imagination and divert you from the real issues, such as were building something were not gonna give you a clue about, or were poisoning our staff with radioactive wasted from our experiments, or look a distraction! Why should we listen to this man any more than we listened to Robert Lazar, i mean he actually worked with the aliens technology, not just know a guy who mentioned little green men. If someone wanted to disemminate information in a way that would reinforce an idea, this guy might just be the fella to do it - credible enough to command belief, but fallible enough to invite doubt.
Im all for th probability of life existing beyond our own planet, but i doubt another lifeform would be insync with us. Im skeptical of this man as much as any other bold claim.