It's a good decision taken by Roglic and his staff. It would be stupid to take risks especially with his knee. Moreover, he had no chance of winning or even reach a place of honor.
I am anything but a supporter of Roglic, but I am convinced that of all the favorites, Roglic will be the best prepared for the Tour. Due to circumstances and his clever choice not to participate at the Ardennes. Vingegaard probably not participating at the Tour, or not in topshape. Evenepoel participating, but not in topshape. Pogacar (after the Giro), in shape but without physical freshness to perform three weeks at toplevel.
But I am not sure whether the fact that Roglic will be able to start the Tour best prepared will be enough to win.