Belief in Satanic manafestations as proof of “aliens” or any other “lying signs and wonders” show lack of discernment or worse.
The Bible doesn’t mention aliens, dinosaurs, or anything other than man’s relationship with the Creator.
Perhaps there are other life forms that have their own covenant with God. It is probably none of our business.
Rather than "Satanic manifestations", a more accurate description would be "pseudoscientific nonsense". There's certainly no need to invoke the supernatural to dubunk UFO devotees.
On the other hand, there's certainly nothing wrong the legitimate search for alien intelligence (SETI, for instance).