It doesn't make sense to use --tag as well as --distro, because --distro names a specific distro whereas --tag combined with --family picks the latest distro with that tag. So they are mutually exclusive. However the --help output and man page could be more explicit about this, and the option parser should probably point out the error.
Making this a docs bug. I don't think it's worth the backwards compatibility risk of making the options mutually exclusive rather than just documenting that --distro overrides the others.