ASA slow pitch courtesy catcher question

Question
Our opposing team only had 8 players available for the game and they used a courtesy catcher from us. The courtesy catcher is not suppose to be involved on any plays in the field only to retrieve pitches from what we were told. With the bases loaded, our batter hit a ground ball to third and the third baseman  threw home. Our catcher, not knowing the rule to not field any plays, caught the ball on home plate for what eventually was decided, after a lengthy discussion by the umpires, to be an out. Was this the correct call?

Answer
Hi Greg,

I answered this before but maybe you didn't get it

I'm sorry but I can't help you w/ this as this is a local rule I have no knowledge of, there is no national equivalent.  Many local exceptions sound good at 1st but are not usually written down with subsections for what happens when something like this occurs. You need your LD to spell out situations like this in writing.

In strict ASA SP w/ 8 you forfeit

Mark