Yes, but if he can still get that development with light quarter rep squats then that's quite impressive.
Considering just how much muscle hypertrophie he had before his injury
I don't think it's that impressive- it certainly appears he responded Very
Well to training & Drugs.
Also after surgery to reattach his quads it is usually a stronger attachment.
I know personally 1 powerlifter who tore his quads trying to 900 +
Only to comeback after surgery & successfully squat it..!!
That I do find impressive.