Without getting into whether I agree with this or whether there's any data supporting such a statement, I think you could make the argument that the EV indicator might make users feel like there's a legal entity behind a site that they could go after, compared to sites without EV indicators.

I don't think you can make the argument that businesses don't adopt EV because that'd expose them to legal risk. That's just doesn't fit into my understanding of how the law and courts work. I'm not aware of any evidence or precedence that would support this, and the EV guidelines don't mention anything of this nature either.