A couple of years ago in a 14U championship game we had a similar play unfold. The team on offense had a runner at third, the four hole hitter up to bat, and only one out. The batter hit a sac fly to shallow center field, and the 3rd base runner tagged up for a play at home. The center fielder caught the fly ball and made a strong throw to home. The catcher set up on the line, received a one-hop, secured the ball, and stepped into the base path to make a tag. The runner, who was at least 10 feet from the catcher, put his shoulder down and laid the catcher out. The catcher held on to the ball and the runner was called out. This was my recollection of the play.
The defensive team's fans went crazy, calling for the runner to be thrown out of the game. It was a nasty collision. The home plate umpire just pointed at the catcher, who came up off the ground and showed his glove with the ball in it then trotted off the field.
The field umpire came running up to the plate, ejected the runner from the game, and warned the runner's coach that any other infractions would result in a forfeit. The offensive team's fans went crazy, saying the catcher was in the baseline the entire play, and the runner had to change his path. The home plate umpire seemed visibly upset at the field umpire's ruling.
The umpires huddled, and then they called for the Director. They all huddled, then talked to the head coaches, then huddled again. The Director finally announced that the runner was ejected, the coach was warned again, the fans were warned, and the game resumed.
The ejected player was the starting pitcher and one of the team's best players. I spoke to players and parents after the game, they all believed that the play was completely the catcher's fault for blocking the plate before he had the ball. In speaking to them, I began to question what I thought happened on the play.
A few weeks later, I received a five second video clip, via email, from one of the parents on the catcher's team. It confirmed everything that I remembered, except the catcher was set up blocking the base path from the beginning. That said, he had the ball secured so early that the runner was three strides from him and had plenty of time to slide around the play. The runner also never slowed down or changed his path as several parents claimed...and the collision was even worse than I remembered.
After viewing the clip, I still wonder why the home plate umpire had a problem with the field umpire's call and how so many fans for that team saw the play as legal. So now, when I read a version of a play, such as described by the OP, I always wonder how the other side saw the play and how the umpires saw it. My bet is that it was a completely different play in their eyes.