This is for sexual activities in the public and just being nude does (usually) not qualify for that. Somebody could try to go after you for molestation but that is pretty unlikely. Even being completely naked should usually not get you into real trouble besides the police asking you to get some cloths or leave the place. But nudists indeed prefer a bit of separation to avoid any possible conflict.
If the police asks you to put some clothes on then, well, you can't walk nude publicly. They won't let you go without doing that. That was my entire point.
If you meant, you can walk nude in public without fearing draconian punishment then, yes, Germany is luckily a country having a sense for proportionate punishments.
