[Cayde's going about this in a way that's fairly clever -- roundabout, to the point where Connor isn't even aware that he might have been fishing specifically for a certain subject.]

It is a lack of foresight. The moment that it was discovered there was once a sickness on that planet that wiped out all organic life, there should have been more concern than there was. More research done.

That isn't even rational sense, it's just common sense.