If the network splits, miners have a right to attack the minority fork due to transaction replay between the two changes. A bilateral split to allow two independent chains to exists requires preventing transaction replay between the two chains. No one can tell the existing protocol to fork off.
Transaction replays should be resolved one way or another. That's not an argument that justifies attacking.
Neither miners, business nor most users want a chain split, largely because of replay risk and the associated confusion of temporarily having two "bitcoins." However, if the minority chain makes the necessary changes to prevent replays, then there would be no need for majority miners to mine empty blocks on the minority chain to protect against them (because replays wouldn't be possible).
So I don't see what all the fuss is about. If a minority wants to split away from the hash power majority, either they should do so in a way the doesn't disturb or impose risk on the majority network (i.e., add replay protection, etc), or they should recognize that the majority is incentivized to protect its interests (which may include mining empty blocks on the minority chain). What else would you expect?
If they decided to split bitcoins then let them be. If it will happen bitcoins price will be split into two and there will be a price meltdown but that meltdown is already being observed by bitcoin users since they view it as a chance to buy cheap bitcoin. Another thing also that will solve the problem of bitcoins shortage in amount and it will be nice to hold both of the bitcoins while they are cheap.