You're a quite funny guy.
1. That's a different source. You don't know whether the first agrees with this. Beware, you might not get what you want.
2. "Color is the byproduct of the spectrum of light, as it is reflected or absorbed". Black absorbs quite a lot, don't you think?
3. But this part is the most fun: "CMYK stands for cyan, magenta, yellow, black -- the four colors that make up the standard printing process". Yep, that very article calls black a color.
So you combine the two sources and get that black is a color that is the absence of color. Cool.
Why do you guys keep pointing out texts that disagree with you? You're making this way too easy.