Actually you started talking about something that does not exist, has no evidence of existing and isn't any the more relevant. I could turn around and say 'Hey, what if the tooth fairies turned up and magically transported us to another planet?', after all, that involves contact with another race, doesn't make it any the less without reason.
Considering the rest of the conversation was about the surviveability of alien races other than ours with the Shivans wandering around, it's interesting to question when and where the Sathanas first arrived. There is no great evidence other than conjecture as to where the Sathanas come into play, the later they appear, the greater the possibility that there are other races to encounter because their stars have not been destroyed.
That is why it is interesting to note that the Ancients' don't, to the players' knowledge, seem to have encountered them, because if they were around then, there is a much lower possibility of us encountering other life forms.