Roethlisberger, in fact, said that he wished the best for Harrison.
"James has to do what James has to do. It's not like he called and asked me if he should or not," Roethlisberger said. "James was out there -- he's a free agent, he has to do what's best for him and his family. I wish him the best. I've had a lot of good years with him."
The Steelers released Harrison on Saturday to make room for right tackle Marcus Gilbert, who was returning from a four-game suspension.
Roethlisberger said he wasn't overly concerned that Harrison could share information about his former team to his new one.
"That's on James. If they want to ask him about every single piece of information he has, that's what this league -- other people do that, too," Roethlisberger said. "I'm not worried about it. We don't play them this week, we don't play them next week. So we'll see."
Harrison signed a one-year, $1 million contract on Tuesday that will pay him a prorated base salary of $58,824, per sports contract website spotrac.com. The 39-year-old will be eligible to play in the Patriots' regular-season finale against the Jets on Sunday and the playoffs.
To make room for Harrison on the roster, the Patriots released linebacker Trevor Reilly. The 29-year-old Reilly was signed to New England practice squad on Oct. 12 and elevated to the active roster on Oct. 25.
Harrison recorded a franchise-best 80.5 sacks with the Steelers, but saw his role decrease as the team transitioned to more pass-coverage responsibilities for outside linebackers Bud Dupree and rookie T.J. Watt.
The 2008 NFL Defensive Player of the Year and five-time Pro Bowl selection, Harrison has recorded 82.5 sacks, eight interceptions and 570 tackles in 191 career games with the Cincinnati Bengals and Steelers.
Harrison is perhaps best remembered for his 100-yard interception return for a touchdown in Super Bowl XLIII against the Arizona Cardinals.