The Kilrathi interpretted events as they saw them, perhaps not as they happened. If space ships landed on Earth several thousand years ago with the kind of weapons we see in th WC universe, I could see people thinking they were some kind of gods, even though they weren't As I said, there is nothing anywhere that supports the idea of the Steltek creating the bugs, in fact if anything there seem to be evidence to the contrary, the fact that the artifacts so far discovered seem to indicate the left this region of space well before the "Star Gods."
The myth around the Star Gods is that the Kilrathi assembled a force to fight them, but the Star Gods scorned the force and left, promising to return when the Kilrathi became worthy. How this scorning was done, is not explained. Did they wipe out the force with an orbital bombardment, or some other attack that didn't fit into Kilrathi combat? I can't imagine someone just telling the Kilrathi they were unworthy and then leave and the Kilrathi believe them. The Kilrathi would interpret the events as they cowed these so called "gods" But I'm getting off point.
The "Star Gods" left and did it such a way that the Kilrathi still saw them as gods. Now assuming the "Star Gods" are the Nephillim (I recall eons ago when I used to be here more, LOAF mentioning a reference that did explicitily state this), why leave? Nothing that Confed's discovered in this area of space would have been a threat to them, they could have had a nice empire with human, kilrathi and other species as their slaves, food source, whatever. Something made them leave. Maybe they truly were looking for a challenge, but I have a tough time believing that. Something made them leave and the only species in the neighborhood we know of who could have done that were the Steltek. Yes there could be another species. And even if was the Steltek that "banished" them, it doesn't mean they created them. I've got some kind of Frankenstein fixation, I guess. As for telling the Kilrathi they weren't worthy, why not? Why tell them that there was an even bigger kid on the playground. It could very well have been a way to save face.
As I've said before, I have no firm evidence to prove this theory, but it isn't hard to make it fit the facts. Does that make it the right answer? No. A lot of people can come up with a theory to explain an event, a natural phenomenon, etc, and there theory seems to fit the facts, but it doesn't mean it is right. We'll have to wait to see what the next WC game says. Hopefully one of these days we'll get an answer. And as I've always said, it's fun to throw these ideas out.