Who said anything about that? This has nothing to do with the idea that Aliens crash landed in Roswell. The universe could be teeming with life, that doesn't mean they are flying around down here. BTW, I am a UFO buff of at least 30 years, was a "true believer", have read up on it for ages, but it came to a point where the evidence was just lacking. I am agnostic on the subject, but being from the Midwest, close to Missouri, I say, Show Me!
Occam is my friend, and so far, this "smoking gun" could be alternatively explained by any number of alternative hypothesis that would easily be more plausible than "Aliens have the technology to cross vast stretches of time and space, but OOPS!, poor aliens go BOOM."
Note that NOWHERE, have I dismissed, out of hand, the possibility that an alien craft crashed int the NM desert in 1947...Just that there a whole lot of other more likely posibilities that need ot be considered first. Shen one considers the state of classified technologies, the cold-war animosities and the info/disinfo wars that ran concurrent with the cold war, It just seems obvious to me that one would start at the most likely course of action, and winnow waway the possibilities.
Consider this...did NM Indian-Americans develop metalurgical-ceramic technologies that would have explained the, "debris," found by Brazell? Is this in your opinon more or less likely than an alien crash?