I think we should put his penalties in context of overall play.
Over his career King averages 7.5 yards lost per year due to the penalties we're talking about.
Taking both King and Pinion's career averages and an average number of punts in a season (75 or so),
Marquette King provides an extra 14.5 yards per game in field position over Bradley Pinion.
Once we penalize him for his unsportsmanlike conduct penalties in this average field position per game,
Marquette King provides an extra 14.1 yards per game in field position over Bradley Pinion.
So, if you want to make a big deal out of his unsportsmanlike penalties, that's the math on the complaint your making: King is only 14.1 yards per game better than Pinion instead of 14.5 yards per game better than Pinion.
EDIT: The other way to think about this is that if Marquette King got an unsportsmanlike penalty
every single game he'd be more or less the equivalent of Bradley Pinion (an extra 14.5 yards of kicking efficiency minus 15 yards for our imaginary penalty every game).
[ Edited by PopeyeJonesing on Apr 2, 2018 at 7:15 AM ]