Are morning or breakfast blends/roasts more of a purgative than other blends/roasts? Coffee consumption and morning bowel movements. Are morning or breakfast blends/roasts more of a purgative than other blends/roasts?
No.

Breakfast blends are simply coffees which are blended to present a particular flavor.  Typically breakfast blends are lighter, and cleaner which are appetizing as a morning drink as opposed to a heavier, darker blend.  Honestly, there's no reason why this is a 'breakfast' blend, other than it has become pseudo-standardized by so many roasteries using the name connected with this style of blend.