This is coming from California, a distinctly capitalist state, and refers to a list published by the US Federal Department of Justice, which reports to a distinctly capitalist (or... at a minimum, a distinctly non-communist) administration.
It also doesn't get in the way of the US's (already extraordinarily loose) firearms sale and acquisition doctrine which regularly costs innocent lives with the pretext of resisting a tyrannical government (which, it appears, people aren't actually that interested in doing now that one's in power).
What lefties? From my non-US perspective, all people supporting this are definitely on the right, including the democrats pushing for this.
Also literally no idea what this has to do with communism, care to enlighten us? Or is it just a catch-all phrase for anything bad?