It isn't really completely fair to say he has a Nikon bias. He clearly prefers Nikons but he does a really good job of saying why in his articles. Very rarely does he not have a clear reason for his conclusions. He reviews a lot of Canon products and usually speaks very highly of Canon lenses. He occasionally makes little comments that seem tilted against Canon but not in his main conclusions - for example he has a rant about the "rate" button on the 5d3 and doesn't see why a serious camera would have that. I can see why wedding photographers might like that alot and I find the button handy to mark the beginning and end of a panorama or HDR series. That's not enough to call him biased though.
He shoots mostly static landscape shots and has zero tolerance for noise. He shoots with a lot of Zeiss lenses and even when he isn't seems to be almost always manually focusing. It isn't hard to see why he'd prefer the Nikon D800E camera for his application - it is very high resolution, no antialiasing filter, and the autofocus weaknesses relative to the Canon options are a non-issue.
If he was shooting a bunch of action shots and was trying to say the D800E was a better choice than the 5D3 or the 1DX it would be a Nikon bias.
I think that almost all of the people that read this board are sophisticated enough to draw their own conclusions and just need good information. Diglloyd provides that. I don't look to him to tell me what to buy, I've got a wife to help me with that.