St Mirren struggling to keep hold of Dorman
The 26 year old impressed at Love Street last season after arriving from New England Revolution last January.
"It was a real blow for MLS when Andy left as he was one of the best midfielders in America," Williamson told the Daily Record.
"He wanted to get back closer to home and St Mirren gave him that opportunity. He's loving life in Scotland and is really happy with his situation.
"(St Mirren manager) Gus (MacPherson) has been so good to him.
"But a player with Andy's abilities will always attract interest from the UK and Holland and I know plenty of MLS clubs would love to bring him back."