The former Manchester City technical director statement's come after Liverpool publicly apologised for their conduct in pursuing van Dijk, which also included a withdrawal of their interest in the Dutch defender.
However, Rigg still believes the move is possible, but the superiority in negotiations has now swayed to one side.
"It's all about putting your club in the strongest position you can from a negotiation stance, and Liverpool have lost that now because they've backed off.
"So, naturally, Ross Wilson and Les Reed don't want to lose the player because they've just signed him a long-term contract.
"Liverpool have obviously done their work over a long period and think he's a player they can build their squad around.