Van Persie was infuriated in the second-half when Williams blasted the ball at his head from two yards as he lay on the ground after he had been fouled. Referee Michael Oliver booked the Swans captain and Van Persie for his reaction.
However Ferguson's extraordinary remark - after his side's off-colour display - was seen by many as a way of deflecting away from a poor performance
"The Van Persie situation you can clearly see that he could have been killed," Ferguson said on Sky Sports News.
"The FA has got to look into it regardless that he has been given a yellow card. He should be banned for a long time because that was the most dangerous thing I've seen on a football field for many years.'
Looked at again though, it seems like an instant reaction from Williams and whilst he was guilty of kicking the ball away it didn't look like he had time to think about hitting Van Persie in the face.
Not surprisingly Williams, 28, insisted after the game he did not deliberately kick the ball into Van Persie's head.
"I just kicked the ball in frustration and obviously not trying to hit him square on the head," he added. "Everyone's going to have their own opinion but from my point of view I tried to apologise on the pitch but it all flared up."
QPR boss Harry Redknapp , speaking on Monday ahead of his side's Boxing Day clash with West Bromwich Albion, said of the incident: "I don't see how he was going to be killed.
"He kicked the ball at him. I have seen worse things on a football pitch."
The view was echoed by Wigan boss Roberto Martinez who managed Williams at Swansea -"I can guarantee you he is not the type who would do that on purpose," he said.
Typically, Ferguson who is a master at deflecting attention away from his players has seen the game itself pushed to the inside back pages as the Van Persie incident has dominated the headlines.