Originally Posted by
teledude
I know that - I was more confused as to why I am in I when no business cabin exists on the flight

It is odd and makes little sense especially when you book similar flights on aa.com which describes the options as First or Business when, as you say, it's the same aircraft in the same cabin. For elite qualification on AA it actually makes no difference but for BAEC it's quite a reduction.
Sadly, logical or not, that's the way it is.