Or perhaps if you want mutable contracts based on intent, you could use one of the 253 legal systems that already provide you with that.
What's unfortunate is that it's taking the form of a dystopia. Instead of realizing that humans are a factor of the equation, and people doing business in God faith... We're entering a ruthless period where anything goes, and because it's all anonymous no one feels bad about it.
There's crazy potential in the ideas here, but it's way too Wild West.
Not possible without proof-of-work
All they need to do is show two coflicting blocks signed by the "approver"