The problem for the Moclans was about having a relationship with a FEMALE. ANY female. That it was a HUMAN female was not the point. And not actually human anyway, remember Talla Keylai is Xelayan, as is/was Alara Kitan.

As for the eye color, how about a rather obvious solution, or at least pointing to one:

Pink eyes = "Female."

Blue eyes = "Male."

I really don't think that you can compare the Moclans and the Kaylons, the Moclans are in the midst of social upheaval where some members of their culture, like Bortus, and the Union don't like there practices, which may lead to confrontation down the road. I think the Union overlooks their cultural values because they need all the allies they can get in the case of a Krill attack. The Kaylons on the other hand are genocidal, they even said it in the episode that they view Humans as inferior and desire to exterminate them like they did their creators. The Moclans can be reformed maybe, the Kaylons are programmed to kill and can't be reasoned with. I just hope that their is a logical solution to this and that they don't get the Borg treatment where they got weaker after every appearance throughout Star Trek and Voyager.

The most obvious "solution" will be some kind of tear-jerker thing where Isaac's "Feelings" about Dr Finn will permeate the entire "collective" as Hugh was going to do with the Borg.

But all the discussion about the Moclan engineer's "crime" was about him "interacting with" a female. Species never came into it. The Moclans don't allow for "interaction with" ANY female, including their own.

I think we can be pretty confident that Earth will not be destroyed.

The reason for that, though, remains unclear.

It may be that the whole thing is just a test to see how Earth reacts.

Something like the Melkotians basically did - perhaps without realizing it - in TOS "The Spectre Of The Gun."

Well we knew that Isaac couldn't resist saving Ty! But who could? That child is so cute.