This might be a case where they compressed too much for coherence.
Yeah, there was the other guy. But in my mind, not enough had apparently been done to confirm a superficial and partial similarity of symptoms.
To give an idea of the dissonance, I'm remembering somebody (I think it wasn't Miles O'Brien who got the line) encountering the Cardassian systems on Deep Space 9 and complaining that they weren't triple-redundant.
In academia, we call it parsimony in a way that doesn't quite seem to match a dictionary definition that I just dredged up on line: It's when an explanation seems straightforward and satisfactory. For me, that was missing.
I think a challenge for script writing here is keeping the story moving without dragging this too far into soap opera territory. How much do we really want get into the weeds here?
Maybe the writers thought this was too deep in the weeds. Maybe they just ran out of episode time. Maybe we agree they didn't get the balance right here.