Strieber's account illustrates the tenuousness of relating such experiences. It would be easy to discount the experience as suggestibility (the passages Strieber read earlier dealt with a similar experience), although it's equally easy to suggest that we may be most able to perceive alternate universes in a quasi-conscious state, and that perhaps the drone had somehow enabled such an experience after Strieber's reading precognitively prepared him.
Regardless of where one falls on the issue, Strieber's account is an intriguing reminder of just how little we know about the boundaries between reality and non-reality.
The author of this post echoes Greg Bishop's thoughts on the nature of Whitley Strieber's recent "contact" experience. Indeed, the central mechanism behind the UFO phenomenon seems to be less technological that "mystical," for lack of a better term. I'm convinced we're dealing with a stimulus with profound implications for human consciousness, in which case liminal states of awareness might help our minds amplify a "signal" that goes otherwise unnoticed. (A rough analogy can be drawn to Nick Herbert's concept of "quantum tantra" for establishing a nonverbal rapport with the "outside" world.)