That is fucking awesome. XD
When has Jenova actually been known to cause death, other than when Sephiroth was also involved? All Ifalna speaks of is mutation.
Which may be all that she is, and certainly makes for a more interesting story anyway. A Lovecraftian horror of nameless origin and uncertain vulnerabilities makes for a far more terrifying notion to me than something we can easily pin down in scientific terms.
However, the similarities are striking and I feel the notion is quickly and unfairly dismissed based on pre-conceived assumptions that lay outside the canon material -- e.g., "Jenova brings only death," "Jenova survives by absorbing Lifestream and has no means of establishing a self-sustaining system," etc.
Like the fandom assumption that hung around for years that Jenova was doing exactly the same thing as Lavos (they aren't even remotely similar beyond both being from space), these are ideas with some degree of sense behind them, and maybe you can see why it would he assumed if the canon was tilted the right away or there was established precedence related to the narrative, but none of that is the case.
Just like the Phantoms from The Spirits Within appeared to be space-born eldritch horrors until a very simple scientific explanation revealed otherwise, Jenova feasibly fits into their same mold. The similarities are more than a little striking.
Of course, that would make Jenova a less interesting terror than she currently is. As Mog said, this current need to exorcise all the mystery from literature is harmful both to the work and discussion of it. However, I'm not about to dismiss all the similarities just for that reason's sake. If anything, this kind of discussion is exactly the kind of thing we should have since the mystery has been left intact.
I like the Omega theory as long as it doesn't become canon.