Note that putting it in container changes jack shit, if it still has network access, it can scan your network anyway...

That's why VLANs are nice, as is requiring your container system (or VM or whatever) to attach its vNICs to a VLAN-tagged bridge on the host rather than the untagged interface that your trusted software uses. If the only thing that the container can hit on your LAN is your router, and your router refuses to forward traffic from that untrusted VLAN to anywhere other than the internet, then that cuts off another avenue for intelligence gathering.

That all assumes that you can't exploit the container daemon to get root, of course.