Yet another idea that directly contradicts what the episode tells us.
But there's enough wiggle room on screen to allow it. For instance, in the teaser Krako's boys make a drive-by hit on the landing party, and one of Bela's men is killed. But it's not like we see an autopsy and burial. Maybe the Iotians have a natural ability to play possum, and that man was just dead enough to fool McCoy's cursory glance. We did it as kids because it's fun.
And maybe all the bullets are fake, and all the Iotians know it. They're just LARPing it up, because they are "bright, imitative people" who evolved in a natural environment that gave them the survival skills of opossum and chameleon (they're classic Italian-Americans now!). And having reached the post-scarcity stage of development, what better way to spend their time? The Iotians are using what nature gave them and doing what they love.
This interpretation also makes the episode more plausible:
• How many aliens could really be such perfect twins of Earth's homo sapiens? The "Iotians as chameleons" theory makes it one less case. They are truly the Zeligs of outer space!
• How many times could Kirk really cheat death and beat alien opponents at their own game, on their turf? This can be one case where he only thought he did. And he still has an incredible batting average.