The thing is we will never truly know what was said to Arbery. They could have said they wanted him to wait for the police, they could have said "Stop right there ***** or we will shoot!". We don't know. And we will never find out for sure. That's why you have to look at what evidence we do have. They tried to stop him, while visibly armed, and had no right to do so. By all apparent evidence, Arbery had every right to defend himself. Why does this part puzzle you and not that the McMichaels tried to do an illegal stop when the elder should have known the law, knew what he was doing was illegal, and yet he did it anyway?