if your point is that wingspan might help a player playing out of position like Powell...ok, I'd agree.
if it's that Portland can get away with playing Powell at SF for most games, in the regular season, I'd say probably, but it would be exposed in the playoffs
on the other hand, if somehow Portland added a Simmons or Siakam or Grant or even Nance, without trading CJ, I'd think you'd have a hard time arguing that Powell should stay the starting SF and Siakam or RoCo should go to the bench. The Blazers would be better off with a quality SF that wasn't 6'3