[@Lovisa Coldeyes]I assumed that any cyborg in this setting would have firewall, antivirus, and anti-spam software.  Otherwise you're asking to get your brain hacked in a place like this.

His implant isn't a psionic power, letting him bypass network security and acces the circuits themselves.  It just makes his brain wifi enabled, and since he's controlling an avatar at the moment, he couldn't really do much more than send you and instant message.  He might be able to hack you if he isn't in an avatar and you get close to him, but a cyber arm doesn't really need a wifi connection except for diagnostics, so you could turn it off if you don't trust him.