your evil twin said:(I do still believe Skynet's story about being built with alien technology, though. It's been said that Skynet is unreliable, but as far as I'm aware that's because of giving bad dates, which seems more a case of developer error than Skynet error. I can't imagine the developers wanted us to think the computer was making up stuff about aliens.)
It's a bit of a cop-out to assume Skynet was lying or confused about that one word, but since it is one word rather than a whole story it's not hard to explain anyway. It could just have meant "alien" in the sense "foreign" - Russian or Chinese, for instance. When Sting sings "I'm an alien" he's not telling us he came from another planet. Similarly, the words "alien technology" with no qualifiers are more likely to mean "non-US" than to casually inform us there are extraterrestrials.