We generally mean an asterisk as a glob wildcard, and *nix definitely doesn't match Linux. There are vanishingly few operating systems whose names match this glob, and all of the ones I'm aware of are either true UNIXes or Unix-likes.
One of my favorite examples of this precision-be-damned absurdity is from the wiki page for Unix-like (https://en.wikipedia.org/wiki/Unix-like):
> Other parties frequently treat "Unix" as a genericized trademark. Some add a wildcard character to the name to make an abbreviation like "Un*x"[2] or "*nix", since Unix-like systems often have Unix-like names such as AIX, A/UX, HP-UX, IRIX, Linux, Minix, Ultrix, Xenix, and XNU.
Of these, zero match `Un*x` and only "Minix" and "Xenix" match `*nix`.
If we want to talk about the category of OS that includes both UNIXes and Linux, I wish we'd just call them Unix-like :)