tag play at home-catcher in baseline question

[DG]

Incidently, I will add a play I saw today. The catcher was blocking the plate for a runner coming home. The ball arrived about a quarter second before the runner. The runner slid into the catcher but could not reach the plate because it was blocked. The ball bounced out of the catcher's mitt in front of home plate. The catcher reached out, picked up the ball and tagged the runner. The call was an out, because the runner had still not reached the plate. I believe that once the ball was not caught, the catcher no longer had a right to block the plate and the ruling should have been obstruction, runner awarded home.