Less laconically, distros generally refer to the userland parts of the operating systems rather than the actual kernel. FreeBSD does not use the Linux kernel so calling it a distro, which typically refer specifically to Linux distros, wouldn't be accurate.
Where are you messing with userland-only options? In my experience a Linux distro not only comes with a kernel, it's almost always a kernel specific to the distro. So I don't understand that reason.
As far as Linux versus not Linux, "distro" feels fine to me for Unix systems.
Less laconically, distros generally refer to the userland parts of the operating systems rather than the actual kernel. FreeBSD does not use the Linux kernel so calling it a distro, which typically refer specifically to Linux distros, wouldn't be accurate.