Don't know if this has been posted. Ever notice that the new ethereal looks just like the old Genestealer Magus? The greater good appears to be the hive mind.
In short... the C'Tan view every race as a slave race... and you can never have too many slaves. The Tau are perfectly suited to life in a Necron-dominated Galaxy. They're intelligent, they don't live long, and they don't venerate an already-existing psychic presence. They aspire to be "cogs in the machine", and are also relatively free of the Warp, which implies that they weren't created by the old ones and are thus exactly the kind of race the C'Tan had hoped would be in power when they returned.1. The C'tan don't need another slave race, especially not a meaty, annoying, preachy one. If they found a bunch of stone-age blue cow people, I think they'd be more likely to eat them than give them uber pheremone leaders and guide them.
And is perfectly suited to the purposes C'Tan, which infected humanity with the Pariah gene.2. The Tau don't have 'no warp presence.' They have a meagre presence which doesn't allow them to develop psychic powers. That seems far more natural than designed.
"Warp Storms", meaning every ship that set out towards their general area was destroyed. It probably only took the loss of a single ship to get the Imperium to decide "Hm, we should go around this area of space for a while" and sparked no more scrutiny than that.3. The developing Tau were shielded by 'coincidental' warp storms which cropped up just as a fleet set out to exterminate them, and remained while their accelarated development took place. That's not something the C'tan can really arrange.
The Deceiver works in mysterious ways. I'd give you page numbers for the fluff in question, but I don't have my Necron codex with me.Yes, there's a lot of evidence of wierd stuff in the Tau development, but the Necrons? Hmm.. It just doesn't fit.
Some of it's very good. Yeah, the Adeptus Mechanicus stuff is irritating, and so are the sections with the Black Templar; but it's really no different from the "IG face Tyranids and die" sections that make up the bulk of the text in the Tyranids codex. When a race has a perspective that's so completely alien you can't write from their perspective, the only option is to write from the perspective of someone else, which creates the ultimate in an untrustworthy narrator... because if you can't get into the mind of a race, what chance does Joe Guardsman have while staring down the barrel of a Gauss flayer?Then again I don't like the necron fluff.. They could have just scrawled "ZOMFG! T3h C'tan pwn J00 with t3h cannon!" on every page and it would have been about the same effect.