He said that had the offer to join Toulon come "several years ago" he would have strongly considered it. Instead at this stage of his career the Dynaboars offer was better.
"There was an option to go to Toulon, plus other teams as well... but it was just the wrong time really for me to go to Toulon," BBC Sport quotes Williams as saying.
"I think if I'd had the option several years ago and I was out of contract I would have done it."
Williams was capped 87 times for Wales and scored 290 points.