Thus, taken together, your second statement strongly implies two things 1. That anger was selected because it had a direct effect on differential fitness and 2. that no other hypothesis could account for this development.

I didn't infer either of those from his statement. He simply stated an undeniable evolutionary fact: anger exists because our angry ancestors had more kids.

Nothing there suggests anger was directly selected for, it's perfectly reasonable to think anger was simply associated with a trait that improved fitness. This is especially true if anger is an undesirable trait. If you assumed anger was selected for, but realized it was undesirable so that selection did not make much sense, you would need to recognize that you were confused, and start asking more questions. You'd soon realize that anger was associated with other traits, and could "piggyback" on desirable traits.

Then the statement makes perfect sense, and since it is clearly not attempting to describe why anger is here, you understand that anger is here because it was associated with desirable traits, which is why we can bemoan the concept of anger at all.

Also, everything I've read from Eliezer so far screams "ABSOLUTELY NOT!" to #2. So too, I never would have made that inference from his statement.