I get a lot of child porn link spam and am currently looking into OCR software to identify images spam bots post, because the spammers have been hard at work at circumventing any other measure i put in place. With that kind of thing being "spam", i can't be nice about it. I need to be zero-tolerance on any detection, even if it may be a false positive.
As for why it's not reviewed by a human: That may not scale. My forum is rather small, 30000 unique visitors per month, but even so, with a team of three people, there is simply no way to look at everything identified as spam. And going by the contacts we get from users about false positives, even if i assume 10 times as many things are false positive than people ask us about, we're still below 1%.
Also, at a wild guess: With an account as big as yours, maybe you just went past a total size limit for all the repos in your account, looking like a bot trying to treat github like a storage system.
Lastly, something meant to be friendly advice: I understand that you're a little upset, but going to the effort of writing such a big blog post, and using that strong language for something that did no actual damage is over the top. This may not be part of your daily dealings, but before you attack github over this, i invite you to try and spend some time to think about how you could write bots to abuse github, which is pretty much a publicly writable storage system, and how you would counteract such abuse.
