What Are They?
The hypothesis of advanced machine intelligence severely weakens one of the main skeptical arguments against UFOs. This is that an advanced technological civilization is not thought to have much durability. Skeptics see our own technological civilization so rapidly spinning out of control and extrapolate this feature to intelligent life elsewhere. Now, advanced technology wielded by biological entities may indeed be inherently unstable. But it is not so clear that such a condition applies equally to advanced machine intelligence. If not, the extraterrestrial hypothesis becomes much more tenable as a way to explain UFOs.
I've harbored similar ideas, even attempting to interest a publisher in a book to be titled "The Postbiological Cosmos." (The publisher declined on the grounds that the concept wasn't interesting enough.)