Gary will continue as Chairman of Board and, as such, will still be calling the shots, at least from the background:

Company Founder, Gary Stern, will step down as CEO but continue as Chairman of the Board. Dave Peterson will continue to serve as Vice Chairman of the Board. Gary and Dave will remain the controlling shareholders of the company and serve in executive roles on a project basis. https://www.businesswire.com/news/home/20221220005218/en/Stern-Pinball-Announces-Leadership-Expansion

So if the CEO is taking the company in a direction that Gary isn't on board with it will likely vetoed anyway, assuming Gary has the votes of the majority of the other board members. Relinquishing the CEO job simply frees up Gary day-to-day. However, if anyone thinks he still is not taking a hand in things I would beg to differ...