Agreed that Bigelow did not move the ball.
Here is the way I look at it.
What do ants think about humans? What are we to them?
We probably exist as “natural phenomenon” like earthquakes and thunderstorms and floods.
In my view that is how humans would react to aliens that were “here”.
There would be nothing to make sense of—it would appear to be background “noise”.
Because—the ants and the humans both make the same mistake—they believe they are at the top of nature’s pecking order for intelligence.
If he knows for a fact that aliens from outer space or another dimension are here on Earth, now, let him name one, and prove that one IS an alien. Otherwise, he is just blowing smoke.