Well, two reasons:
1. Anarchists simply have little to no knowledge of them. They are not a widely discussed subject in western political discourse or the media, as far as I can tell.
2. Anarchists see no point in discussing them because they find themselves opposed to Maoism, of which the Naxalites are a primary sect.
It really is very misleading to ask, "Is it because they've taken up Maoism?" They took up Maoism forty years ago. That's four decades compressed in a single question that makes it seem like it was only yesterday that they rallied around Mao Tse Tung's doctrines.
It's also misleading to ask, "Just another case of first-world-centric ignorance?" It's as if you're under the impression that the Naxalites are noble peasant warriors simply fighting for their lands. The Naxalites have since been apportioned into various Maoist and Leninist parties and cadres, all of them being divided in any significant manner only by an adherence to either a championing of the credibility of parliamentarian politics or an intensification of decades long warfare. Furthermore, these Naxalite Maoists are in partnership with the larger Maoist establishment of southern Asia; notably the Maoist partisans of the Nepalese ruling class. This isn't simply a matter of the peasantry taking up arms against landlords. I didn't fall for that with the Zapatistas and I won't fall for it with the Naxalites.