I think there is nothing to argue about. The statement made was merely an observation with the behavior of animals in relation to human.

Firstly, Im not quite sure if the statement is justifying that either it is ok to be gay or polygamous just because animals do it?

Secondly, would it be justifiable to say that humans are more rational than animals that they know what is right and what is wrong?

Thirdly, the term moral, or what is right and wrong varries from person to person. It is established by cultures, religion and the upbringing of the person. your right might be wrong for me.

Fourth, respect, a fundamental of harmony, has been thought at home and in school but it seems to be difficult for some people to understand it.

In summarry... The issue is not being gay or engaging in polygamy, neither the lions or any other animals.
Well, you could be an animal barking at each other, or be rational enough to be human and respect one another.