Not really. If anything, using the BD 320 will mean that they have opted for the larger aircraft for the majority of the rotations.
True but I think he was meaning that for the airline it is less revenue and profit effective.
For example, LH could have 120y+5C booked on a flight for which it would suit the Boeing jets more than an A320 as it would maximise the seating capacity much more. Also, if there was demand for say 150Y+10C (again, numbers out of my head), the A321 would be more appropriate. The same works for cargo.
This way the airline is fixed with up to 162 (all Y) seats and a set cargo limit.
Just my interpretation anyway.