play at the plate

I know this same thing keeps coming up but last night our catcher has the ball in his glove and moves to the third base side of home plate (he blocking the plate maybe 2 feet from the plate). The catcher had the ball before the runner was even half way there. The catcher is standing there just waiting for the kid (no idea why he didn't pickle). Anyway the runner crosses his arms and runs smack into our catcher. The ump calls the runner out and "warns" him not to cross his arms again when coming home....

Our league does have a must slide rule too.

I don't understand why this kid was not ejected for malicious contact. That same catcher was ejected during fall ball for the exact same thing (crashing into the catcher) so he was totally confused.

The umps were not really happy with our team at that point in the game. They had ejected a Mom (of course the only game she comes to all year) for obscene language and our scorekeeper ejected himself (lol) before he got thrown out because he was wiggin.

The ump had actually made the following comment to the other coach before the second game (we played a double header against the same team)
"Don't worry this second one will be a short game because they are not going to get any calls". Our boys did win both games anyway but I am wondering if this incident with the catcher was right or not. Why would there be a malicious contact rule if it is never enforced?