Which does raise the question of why there was a Gorn aboard the wreck of the Cayuga.
The Gorn drew up the demarcation line and broadcast it to the Federation, held their fire as promised, and did not consider the arrival of another Gorn ship as a hostile action.
So the Enterprise sending a shuttle to check the parts of the Cayuga’s wreckage for survivors is something that appears permitted and even expected, so long as it doesn’t cross the line.
But any such rescue party would then bump into this lone Gorn who was very clearly violating the demarcation line that they themselves proposed.
Sort of feels like the attack on the colony was unplanned, and that the later Gorn ship was playing damage control while trying to figure out what happened.