Speaking of the phone since that appears to be the cause for resisting. I find it interesting that the report contradicts itself.
The report claims that he stated he was leaving and took his phone. This seems perfectly reasonable to me for someone who’s there voluntarily and decided they no longer wanted to participate. Then the officer states he told him they were keeping his phone. At this point it says he picked up his phone. If he had already taken his phone how did he take it again. Maybe the video would clarify what’s going on here or maybe the officer made a mistake when writing the report.
People can come in voluntarily of their own volition for a questioning that, if they didn't come in voluntarily for, would be arrested so that they can be questioned. He was a suspect in a crime and was being questioned. He didn't have a right to leave. He did have a right to ask for a lawyer to be present and to not self-incriminate. But walking out whenever he wanted, or refusing to have his phone searched (assuming they had a warrant for it since they reportedly searched his residence) was not on the table for him to decide.