King was highly aggressive while resisting arrest. He assaulted multiple officers even while he was down. The camera catches on just at the moment that Rodney is up again and is charging the officers (that part is very blurry) and where they've finally taken him down and that's all that the media ever reported.
An expert witness who testified during their trial carefully went through each blow in the video and explained why it was part of the procedure during such a situation.
1991 LAPD Use of Force Chart and how they applied it during the Rodney King arrest:
kingforce
An Account of the Los Angeles Police Officers' Trials(The Rodney King Beating Case)
NOBODY profiled Rodney King that night. It was Rodney who initiated the entire event by speeding at 120mph, nearly causing wrecks and causing the cops to chase him. It was Rodney who wouldn't cooperate. It was Rodney who attacked the officers and gave them no choice but to beat him. The officers weren't looking for Rodney that day, but he sure as hell got their attention with his antics.