ah, now I get what you meant! I totally second that. It'd be interesting to know on which basis this educated guess was made.
I find the time frame a bit cramped. We Germans pride ourselves to be good inventors but I don't think we could have developed space ships that quickly, even under optimal conditions (intact industry, lots of money, no shortage of materials). We have an unfoortunate tendency to second-guess each and everything, including ourselves. That costs a lot of time (but also saves a lot of "If only we had"). I'm curious to see why in this model the development was assumed to be so fast.
I can see what you disliked about my "one guess is as good as any other". I should perhaps have elaborated a bit more clearly.
In my experience, the very same facts can often be interpreted very differently, depending on many factors (education, cultural background, frame of mind, even a bad hair day might influence our way of looking at things). Therefore it's very likely for quite different theories being made from the same vantage-point.
Usually, reality will sooner or later prove one of these theories to be correct or at least more likely.
However, as we are talking about a completely imaginary scenario, we are deprived of this practical proof. And a purely analytical proof would again be based on our different interpretations and thus lead us back in a circle. Everyone would be convinced that he or she was right, because everyone instinctively tends to rate one's owns ideas higher than those of others.
Because neither theory could impartially be proved to be the correct one, I concluded that each theory would be of as much worth as any other.