I vaguely remember this tag pertaining mostly to gay and or pegging, you know, where the bottom reaches orgasm whilst being penetrated by another, but then recently several straight pictures such as post #316148 among others has the the cum_while_penetrated tag. So does the "while penetrated" imply that the "catcher" in the scenario is the one reaching orgasm or no?

In the picture you quoted, only the bottom one is cumming, so I don't really get the question...

The tag applies to the bottom, or else it will be cum_while_penetrating.