Nah, there have been thousands of well documented encounters of non-human entities piloting or exiting the craft, leaving behind footprints and physical evidence, using exotic tech, communicating with eyewitnesses and abductees. There's too much evidence to sweep it under the rug. Ridicule worked well twenty years ago but it no longer does.

That doesn't mean the government doesn't have advanced tech though. They very likely do, there are many documented cases of humans aboard these craft as well.