Flagrant fouls, or even bigger violations, don't normally carryover when changing leagues. The player starts over with a clean slate. If say Lebron James had punched a referee in the face during the NBA finals then decided to play in Turkey, he wouldn't be suspended for that in Turkey. Same with drug & other offenses normally.
If this flagrant foul thing were to be implemented, how about penalties to non-aggressive players? Maybe non aggressive players like to sleep in & show up late? Be late for 3 games/practices, & be suspended a game.
An intimidation penalty. Like: "Player X is afraid of Mr. Thug & refuses step foot in the paint, drive to the basket, or go after any loose ball in his vicinity". A player's intimidation factor goes up with each flagrant foul. And quintuples with each suspension! Eventually non-aggressive Player X refuses to even take the court against Mr. Thug!
New Trainer specialty: Phone user. He calls your non-aggressive player with his cell-phone in an attempt to wake him up so he won't be late. Since cell phone coverage is spotty it doesn't always work.
New PR specialty: Paralegal. He uses legal jargon in an attempt to get the league to reduce suspensions to aggressive players. He's not an actual lawyer though & isn't always taken seriously.