I am getting a bit tired of fixing this lie, which is a still a lie no matter how often you repeat it.
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Let's get more specific shall we?
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You blow into the same horn again, and I agree to most of your reasoning. But not to your conclusion, because it lacks one critical point.
Please answer this and prove me being wrong:
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Where will the security come from? If 90% of the hashpower goes to the legal fork, how easy will it be for those miners to perform 51% attacks on the genuine-bitcoin chain that now only has 10% of the original hashpower?
There is no chance that multiple bitcoin forks or altcoins based on the same mining algorithms can coexist long term. The biggest one will win because it's the only secure network.