That particular question is about installing FreeBSD, so I'd consider it legit, but that's just my opinion. Anyway you might be able to create a FreeBSD jail on GhostBSD (but whether you can or not is a question for their forums, not ours, or daemonforums which is about all BSDs). Or use VirtualBox, which should be supported on GhostBSD. (Though I don't know that for a fact, but I would think so).
But I would also say, if your system is handling GhostBSD without a problem, it really isn't hard to install FreeBSD and get it working. It should pick up whatever network you use on install and use that upon installation, whether wired or wireless. X takes a bit of work, depending upon what video card you have, but it's really pretty easy. If Intel or AMD you install drm-kmod, if Nvidia, you install the Nvidia-driver. As I imagine you're using either XFCE4 or Gnome on Ghost, that might take a bit more configuration, but really not that much more.