But Naughton stressed that no contract has been signed and therefore no team currently has any legal rights to Williams.
"Basically it's just a verbal invitation and an acceptance," he said. "If they want to let him go they can; and if I want to be a jerk and pull him out of there – I technically can."
Naughton also said the Cleveland Cavaliers, based in Williams' hometown, have shown "absolutely no interest at all; no phone calls and no correspondence of any kind."
The summer league runs from July 8-15 and is comprised of 16 teams. Williams worked out individually before the draft for 10 of the 16 teams.
Naughton said Williams has taken this development well and is focusing on the bright side of his current situation.
"I think he's taking it very well," Naughton said. "We were talking about Scott Williams who went undrafted and played 13 years in the NBA. I also tried to stress this to him: Sometimes it's better not to get drafted in the second round because now you can pick the team you want to and get better exposure.
"Obviously, he would have loved to have been drafted, though. I talked to many experts who felt he was as good as a lot of the later first-round picks."
Manuel's agent, Derrick Powell, said he is talking with several teams and should know something about Jackie's future plans the next week or so.