You can't really claim that this creature's natural habitat would be earth-like gravity, that it would have evolved to move fluidly and easily in our gravity.
I can't, but again your 400 people should be able to give us a yes or no on the important part of it. If this was the case any of the witnesses who have seen a live alien moving around would mention they don't move so well in Earth's gravity. Whether that's because they're from a low gravity environment or because they're a race of drunks doesn't really matter.
Even if only ten of them have experiences involving live aliens moving around like this, the testimony of those ten will all mention it if that's how it works. It's a note worthy observation that anyone would make without any prerequisite knowledge.
"There are more things in heaven and earth, Horatio,
Than are dreamt of in your philosophy."
A decade ago teleportation was fantasy, now it's reality. Invisibility was impossible, until it wasn't. We have continued to set limits on our understanding and are continually shown just how limited our understanding is.
Just because the Amazing Randi hasn't found someone who can pass his telepathy tests doesn't mean it's logically unreal. It just means that we don't understand it if it is real, or aren't asking the right questions if it isn't.
Telepathy on a technological scale is already being seriously discussed in mainstream science. There's no reason to assume nature didn't figure it out first. Creatures evolved to the point of interstellar travel could be very very old, with lots more time to explore nature's possibilities. Or maybe they just have nano-chips in their heads like Michio Kaku has been claiming we will have soon.