Of course he would say that. There is this thing called "common curtesy." He's not just going to come out and say the movie sucks even if he really thinks so.
And I doubt he'd tell Rian Johnson if Rian made a superior film to any of his prequels or even his original film (let alone if it was on par with it). I'm sure he didn't say anything like that to Irvin Kershner after watching Empire Strikes Back.
