This is the quintessential “Fox and Henhouse” situation. The evidence is overwhelming but the Pentagon is not about to alter its longstanding course, Congress be damned.
Sure there have been “visitors” over the years, both before and since Roswell. We have a nice planet here, but it is small and mostly water. Probably more important, our solar system is WAY OFF the galactic “beaten track”. So we probably are not viewed from outside as worthy of serious attention or exploitation. Natch some freak show aficionados and primitive life curiosity seekers show up here from time to time from far, far away Most probably leave with the thought we were not worth the trip.
Intergalactic visitors? Hey, anything is possible. But I have really serious doubts on that one.
Bottom line I agree with some in Congress that the Pentagon is covering up. That should come as a shock to nobody.