That sentence looks so utterly silly to any normal human being.
I'm always amazed when the ID-as-trojan-horse-for-creationism folks (which is almost all of them) expect anyone to actually fall for that line.
It's so patently transparent that I can't imagine why they think it helps their cause. It just drives me up the wall, really, when I see it, because it's such a phony pretense. If someone wants to seriously discuss creationism with me then I often will, as I've done a number of times before. But, when they bring up this BS "oh, um, it coulda been aliens, ya know?" my only reaction is "yeah, whatthef***ever!"
And, if we really want to discuss alien intelligent design, then by all means let's discuss that. I'll start things off:
Where are the aliens, if they are designing the course of terrestrial biology?
If the aliens have been here, why do we see no evidence of alien visitation?
If aliens are directing biological phenomena from interstellar distances, by what process are they doing so?
Where did the aliens originate? Did they evolve, or were they designed by yet more advanced aliens? Where did the initial designer aliens originate?
If the aliens did evolve, then why could we not have evolved just the same as the aliens did?
If the aliens did not evolve, and the initial designer aliens did not evolve, then did God create them?
Oopps! Never mind! We weren't talking about God! Aliens designed us..
Strangely, they always balk when I suggest time travelling humans.