His point is we shouldn’t be terrified of selling a player at his peak if the team can fill the void and we can use the money to address weaknesses in the team.
Obviously selling Kane at any point would have been a bad move, but dele and dier are two examples of players that we could have sold at peak and probably found a better replacement with.
Dele was not at peak age when he was flying... He was like 21/22!
Even Dier was more like 24 when he was being linked to Utd.