ermmm, I can't believe a prop designer would give such a simplistic answer for a variety of reasons. Does he design helicopter props or boat props, and in which case mobo or raggie.
Reason for asking, is that drag varies according to design, so no prop designer would ever give a cut and dried answer, in much the same way a scientist like me would add bits onto any answer like, yes, no, but.
A helicopter has huge diameter blades, with not a lot of total surface area, but huge loading on each blade. A mobo has far lower diameter blades, but with massively increased % of area covered for the diameter. Many raggie boats have slim chorded 2 blade props etc etc.
Each have different characteristics. The drag of each, will have similarly disparate drag co-efficients. Hence my question about what sort of prop your friend designs, as the statement that fixed props equates to less drag always, is just not true