People who say "keep politics out of" anything are usually stupid. Most things are political. Implicitly supporting the status quo is political. Leaving things unsaid is political.
Usually the people who pop out that line mean "keep politics that are different than mine out of".
But on topic, punk is extremely political. For example, please review these lyrics from The Clash "Know Your Rights", 1982
You have the right not to be killed
Murder Is a crime!
Unless it was done
By a policeman or an aristocrat