Richard Baker wrote:
Tranya could have been poisonous to humans not Balok's race
I considered that, though did not mention it specifically. It was covered in the general idea that the First Federation knows a lot about the UFP. In the same way that Balok is a token shorthand for an alien, the offering of a drink is a gesture of protocol that would be understood by the audience. After scanning the Enterprise's
data banks, Balok would know what he could safely offer the humans.
(Consider the task of digesting that much information in the time indicated by the story. If Balok himself did not have that capacity, then the Fesarius
must have an amazing cybernet system. How about the sparkly cloth band he wears on his head—is that an interface that allows him to use the Fesarius
and its systems as an extension of himself? How much more is there to the First Federation than meets the eye?)