This may not be a flaw (there are possible ways to explain it, I suppose), but as I went back and reread "Ironman" I wondered why the statues were depections of both male and female humans. Since all three Envoys were male, why would the aliens have any reason to suspect the existance of a second sex? Their physiology was obviously extremely, well, alien to our own, and the concept of two genders may have been completely foreign to them.
Anyway, that's my guess.

-Balanthalus

(BTW, "Stuck" is also my favorite :))