But is that how you ordinarily sell commercial airplanes to airline executives (the purpose of the flight)
I believe the passengers were largely journalists, not check-signing "airline executives." There may have been a few, but I think Sukhoi perhaps saw the purpose of the flight more as selling the aircraft by getting laudatory, wide-eyed newspaper and magazine coverage. And you're not going to get that by cruising super-efficiently at FL350.
I'm not being cynical, for in fact I've been an aviation writer since 1968, when I first joined Flying Magazine.