It's fine to just call it Alpine Linux, since (AFAIK) BusyBox isn't associated with the kind of self-aggrandizing assholery that sometimes leaks out of RMS.
RMS had a very strong point that GNU should have been getting some credit and was arguably more responsible for the 'linux' experience that linux itself is.
It's a weak argument that resembles bullying more than it does anything else.
If that kind of crediting was necessary for something like the GNU project to be known and to thrive, then it should have been solved eons ago by including it as a requirement the terms of the GPL instead of by being indignantly recalcitrant about it later on.
