Keep this in the back of your head.
The odds are that if you're new to USPSA, this was your first sectional match and 6th match total, the RO and Range Master have no idea of your proficiency with a firearm. The rules are in place and apply to everyone, regardless of their proficiency and ability to safely handle a firearm.
If you've got a mag inserted, no one has any idea if the weapon has a round in the chamber.
You're right, it's a game. And they have rules. You broke them, same as the time I got DQ'd for breaking the 180.
One of the reasons I think the sport has such a good safety record is because the safety rules are zealously applied.
Don't give up on the sport just yet. It's a lot of fun, and you meet some great people.
But don't get pissed if you break one of the safety rules and get called out on it.