He's not going to announce to the world that he is potentially not following every last line of the gardening term is he?
I'm not saying he's going to go work full time at Aston Martin, but his influence at the team will happen regardless of the leave. Adrian could indicate to Aston Martin the people that he wants hired during the contract negotiations. Small ideas can spill over from informal chit chats. It's impossible to keep a man like this from influencing things. The man has just spent 3 months telling Aston Martin how he envisions the team to look and the conditions for gaining his services. This has already influenced Aston Martin in a positive way. His utility is not just in car design, but also in shaping the team by making the right demands and having the right people and methods in place. That process started long before his gardening leave expired.