It really depended on the circumstances. Being punk itself wasn't forbidden (though it could get you in trouble with schools or employers since in many contexts the look was still a very scandalous thing). Generally, in the mid-late 80s, in the whole East German system became a lot more lax, they also started easing up on travel restrictions at the time, so a lot more people got to travel into the West for example, there were big concerts by Western artists like Bruce Springsteen etc.

But obviously, punkness often comes along with a general fuck-the-authorities attitude and that in turn made punks more likely to be controlled (kinda like even today a police officer will be MUCH more likely to search a punk for drugs compared to a suit-wearing banker). In general, the government was not too thrilled about that attitude.

This specific guy was an artist/photographer who at the time did photography for an East German fashion magazine, so he had more leeway than most.

Source: both of my parents were punks in East Berlin and my aunt actually knew this guy quite well