No it's not, not by anyone serious.
We know the brain is the seat of consciousness because damage to the brain damages consciousness. There is no other organ in the body where that's true. You can completely replace all other organs without changing consciousness.
You can always find a paper by a quack that posits the earth is flat, that doesn't mean there's serious debate.
I only gave one example and Wikipedia to start with. There's a lot of material out there if you're (rightfully) skeptical of that one paper. I don't even know what you're refering to as "their theory", as the way I read it, they're basically documenting various co-existing theories, and the authors don't disclose which one they find the most likely. I also don't see it as necessary for science to pick one; it's all about theories. I prefer documentation of all possible theories, and see no reason to dismiss one over the other unless they're disproven. I pointed to that paper, because any paper that talks about alternative theories shows the point I was making: We don't know yet. The point was not to claim that they've managed to put together good or bad arguments.
I'll try and read the paper more carefully after work, but my quick read was: they posit that consciousness might not be localized in the brain because if it were, then how would people be able to perform telepathy / remote viewing / future foresight? I can't assert that their non-local hypothesis is wrong, but I can pretty confidently say that the evidence they're using to back it up is unscientific BS.