It's disappointing that the first thought with a result like this is that he's a cheat, but it's difficult to justify it otherwise.
He seems/seemed like someone you wanted to root for, but the margin of victory just raises so many questions.
He's in good form, and the route suited him, but this is not and has never been his specialism. He and his team will point to him losing weight and hard work to explain the improvement legitimately, but he'll now forever have the same question marks as the likes of Froome hanging over him, even if he struggles in the next few days.
I interpreted Geraint's response as him calling Alaphillippe a cheat without saying it, rather than being concerned about the race.