Back in my D-level slow pitch softball days, we had to have 9 to start the game, but could finish with 8 if someone was injured. We could play 10 if we had enough.
OTOH, maybe he was thumbing his nose at OP's team - we don't need no stinkin' outfielders against you! Which begs the question, did OP's team get a ball out of the infield?
HC stated to our HC that is was to punish his girls and in no way reflected upon our team. To be fair, we were WAY outmatched. We were also playing up (and did surprise one team later that day with a win). And for the record, we were no hit so nothing went beyond the infield. But did manage to score a few runs!