Even better, the seller lists them as--wait for it--Record Pista Strada cranks.
As for the flexiness discussion, it's my (totally unsubstantiated) contention that almost no one is ever identifying actual differential flex in cranks or frames. They're either misattributing to flex in the crank/frame some genuine mechanical phenomenon that's occurring elsewhere, or else it's entirely psychological in the first place (e.g., I expect something to feel a certain way, so it does).