If the government tries to fake aliens, they would have to fool the space research community, which won't be easy because they know just how tough it is for life to come to fruition and how difficult it is to travel through space, both the time it takes and the health hazards from radiation.

The other option is to bribe them, but they're gonna look like idiots with all the countless hours of footage and text out there contradicting them. It could happen, though; we've seen just how much doctors are willing to lie when it came to Covid and Vaccines.