Cooper was told by coach Brad Thorn that he was no longer wanted by the Queensland Reds, leaving the playmaker in contract limbo.
He is expected to play in the National Rugby Championship starting September 1, but his future beyond that is unknown despite being contracted for 2019.
And Williams declared that should Cooper “will go magnificently” should he elect to go down the rugby league path.
“I think he would go magnificently,” Williams told Sunday Night with Matty Johns.
“From what I’ve seen, his skills are second to none.
“It’d be awesome to see him in a set-up like Melbourne or the Roosters or somewhere where they’ve got a good system in.
“Just imagine him running behind a forward pack that’s going forward and him doing his magic.”