The irony behind people saying that Discord commenting Fluttershy is his “favorite” in part 2 of “The Beginning of the End” testifies FlutterCord being canon is that, in the long run, bringing back Sombra was part of Discord’s plan to boost Twilight’s confidence as a ruler and her friends’s confidence as protectors. He only said Fluttershy was his “favorite” because he knew Sombra would target her after he said that, and he only faked being hurt to convince the Main Six that they don’t need him to defeat Sombra.

I can’t help but wonder how FlutterCord fans must have felt about getting a slap in the face in the long run because of this.

It's not like this was anything new. Discord said in "Twilight's Kingdom Part 1" that when he was doing it for the ponies "it's mostly for Fluttershy". And in "Make New Friends but Keep Discord" he got jealous that Fluttershy was bringing a new friend to the gala instead of him. Discord admitting Fluttershy was his favorite was nothing new. And considering he revealed that he could've stopped Sombra at any time, even before the Grogar twist, I think it was obvious he wanted Sombra to attack him. I don't think he was really abusing his connection to Fluttershy, it was just the easiest way for him to take himself out of the action.

7305918
Exactly. That’s why I don’t think it was confirmation of Fluttershy and Discord being anything more than friends.

7305929
As a huge fluttercord fan, I would say that you are correct. It isn't confirmation and nothing from the show, including the last episode, makes it canon.

But by golly, it was some sweet fuel to get us excited. And I'll take it.

Well it definitely doens't confirm fluttercord on its own, but it's not refuting it either, since he would've done the same if fluttershy was in charge. He didn't try preparing Twilight because he likes her the most, he did it because as he said, he wants to make sure she feels prepared so she can lead as well as she can.