Anyone who says he didn't go to the ground in the process of making the catch, what you're saying instead is that he could theoretically have caught the ball and stayed upright if he wanted to.
I don't believe that could have been done. His body is coming straight down in an uninterrupted motion, from airborne to flat on the turf.
Yes, his two feet are the first body parts to touch down, but that doesn't prove that he's stepping or running or doing anything other than collapsing to the ground. If you think his falling to the ground was an act completely divorced from the catch attempt, you're being very very generous IMHO.
Bear in mind that, if you slow the video down enough, you can make *anything* look like a catch.