That was a silly flagrant (that Perk did it and that it was called).
Yeah, it was an elbow to the throat...but Perk clearly wasn't looking, it clearly wasn't intentional. I'm 95% certain Pietrus saw that Perkins had his arm out like that so he moved in, caught it on the neck, and fell backwards in dramatic fashion.
Smart play by Pietrus...tricky little weasel.