Spy guy truly made a good point. The original article is about "unusual" methods of reproduction, not about babysitting. Human homosexuality is not a method of reproduction.
For the past couple billion years, plant and animal species have tried all sorts of ways to solve the problem of how to survive and make as many babies as possible. In that time, they evolved a mind-reeling array of solutions
I still want to know if Tidwell thinks we humans are supposed to reproduce by division, since planaria and starfish do that.
No, he did not. Making as many babies as possible is a good way to wipe out your environment. It is a good strategy for bacteria, since it's the only one they have. It is a sucky strategy for most creatures large enough to be seen with a microscope, who live in equilibrium with their environment. If it were a good strategy for humans, we'd have quintuplets every few weeks. The more you live in a stable, long-term sustainable environment, the more the payback for having a few, high investment offspring, as opposed to a lot of low investment offspring. You only have so many resources to invest, and having tons of young isn't necessarily the best investment.
Homosexuality causes resources to concentrate on fewer young, and that's an important strategy to have in your back pocket when an environment with which you are in balance grows precipitously worse--having the entire wolf pack starve trying to support an overburden of kits is not a good plan--wolves are a sterling example of how this strategy works, and why it's a non-trivial contribution to wolf pack survival. Having your nephew survive is better for your genes than having no one in your tribe survive.
I'd suggest a book on this subject: "Why Big, Fierce Animals are Rare". If you'd like to think about it a little harder.