Oh boy, it's this topic! And all of the expected replies are present and accounted for!
In order for a person to be 'gay', there has to be a cognizance of sexuality. How many kids shows really focus on sexuality?
(I'm not focusing specifically on this quote, it's just a stand-in for all the similar answers).
If a children's show depicts a character's parents living together, is that focusing on sex or sexuality? If it has a character's older sibling talk about going on a date, is that focusing on sex or sexuality? What about a younger character developing his/her first crush on a classmate?
In all of the situations above, a heterosexual pairing could easily be substituted for a homosexual one without making the content any more complex or inappropriate. Children don't need to understand sex or sexuality to understand the idea that two people of the same gender can have a relationship.
"LOOK AT THESE MEN THEY LIKE EACHOTHER WHAT DO YOU THINK?!" Is justs stupid. Kids wanna roll down hills and draw on walls, they dont give a fuck about deep issues like this they wont understand.
It doesn't have to be a deep issue. It doesn't have to be the focus of the TV show or the character's defining trait. It doesn't have to be obvious. You don't even need to explain what homosexuality is on-screen. All it would take is for the protagonist's parents to be two men or two women instead of a man and a woman.
A lot of people are assuming that this is an issue that doesn't affect young children, but that's not true because a certain percentage of those kids are/will be gay themselves, and they might become aware of this at a younger age than you might think. If they've never been exposed to the idea before their feelings could be distressing or frightening (particularly given how homophobic many of their peers can be), but if they've grown up thinking that it makes perfect sense for people of the same gender to fall in love, it won't be as big an issue.
Also, on a side note, I'm kind of disturbed by the number of people holding up this or that character as being "obviously gay" based solely on the fact that they act camp or effeminate.