The ref was correct, here is the rule clarification from the rulebook

[Safety Blitz]

Like I say above, they should take the subjectivity out of it and mark it where the butt contacts the ground, you can see that on a video replay.

Question: Are you willing to let the Pitt QB (or any QB) get crushed by a defender when his butt is still an inch off the ground on a slide?
Answer: Of course you aren’t, nor is anyone else who watches football.
I idea of the rule is to protect the QB.
The QB is granted protection the INSTANT he makes any movement in the official’s judgment to initiate a slide. (Otherwise described as his butt beginning to sink toward the turf.)
That is the exact same moment the play is declared over. And the location of the ball at that instant should be the spot for the next play.
It is really quite simple

 

[Pitt79]

Question: Are you willing to let the Pitt QB (or any QB) get crushed by a defender when his butt is still an inch off the ground on a slide?
Answer: Of course you aren’t, nor is anyone else who watches football.
I idea of the rule is to protect the QB.
The QB is granted protection the INSTANT he makes any movement in the official’s judgment to initiate a slide. (Otherwise described as his butt beginning to sink toward the turf.)
That is the exact same moment the play is declared over. And the location of the ball at that instant should be the spot for the next play.
It is really quite simple

Ok, then give it to him where his front foot is, so you aren't penalized for protecting yourself.

Actually, you could say the defender can't hit him the second he starts the slide, but the ball is marked where his butt contacts the ground.

Also, I am OK with the QB getting crushed, if it's blatant call it roughing. It is football after all, you can't expect total safety.

 

[JokePa]

What do you mean by starting the slide?

I thought he clearly began slowing down before the market, but I didn't think he initiated his slide until he was past the sticks.

I think people don’t know what a slide is? Is starting a race not at the flag but when the nascar driver arrives at the track? In school if you have 30 minutes to do a test does that 30 minutes start when you enter the class and not when the test gets handed out? Does a punt hang time start when the punter catches the snap? I don’t understand how a slide can start before the actual slide happens

 

[JokePa]

Question: Are you willing to let the Pitt QB (or any QB) get crushed by a defender when his butt is still an inch off the ground on a slide?
Answer: Of course you aren’t, nor is anyone else who watches football.
I idea of the rule is to protect the QB.
The QB is granted protection the INSTANT he makes any movement in the official’s judgment to initiate a slide. (Otherwise described as his butt beginning to sink toward the turf.)
That is the exact same moment the play is declared over. And the location of the ball at that instant should be the spot for the next play.
It is really quite simple

No, because if his butt is an inch off the ground then surely his legs are already on the ground. If he gets hit before the actual slide of course it’s legal, if the qb wanted to protect himself he should slide sooner