He told BBC Radio Humberside: "I had Will between between 14 and 20. He's a player I'd really be interested in but think he's a Championship player.
"I speak to him quite a bit. If someone else wants to take him in a higher division, that's good for him."
Scunthorpe failed twice with bids for Hoskins during the January transfer when Ian Baraclough was their manager.
The former England Under-21 striker has scored 19 goals this season following his arrival from Watford on a two-year contract last summer.
Under Knill's management at Rotherham, he scored 23 times in 73 league appearances before moving to Vicarage Road in January 2007.