Again, folks are arguing that PCA cannot be ruled out because a walk is a dead ball, and it is absolutely NOT a dead ball.
A walk allows all base runners to advance without peril to the next base. What you cannot do is touch the base and then leave that base, and that's what PCA did.
He was tagged PRIOR to touching the base, and that didn't matter, but when he slid off the base and was tagged with no part of him touching the base, it's no different than standing on the base with a foot on it and lifting that foot off. He is out at that point.
Officially, this is a 2-6 out advancing, and not a caught stealing, because by rule, he was forced to go to second due to the walk, so it couldn't be a stolen base. Therefore, the converse is true that it cannot be a caught stealing either.
This actually happens a few times a year, so I have seen this before.