Hello Eric and Bertrand,
It's nice to see that you're also joining in here.
I stumbled across the action in Eichstätt in a
book about the order and punitive measures in the HJ, more about this can probably be found in Klönne, Die NS-Zeit in Bayern. But I don't have that book (at least not at the moment).
Otherwise I only know of such haircutting measures against HJ opponents, like the "Schlurfs" in Wien/Vienna, who belonged to the working-class milieu, or the "Swing Boys" in Hamburg. In Wien in 1943, the the head of the Youth Detention Centre (Jugendarrest) even demanded that these delinquents "with jungle-like hair" be shaved completely bald. That would be the greatest conceivable punishment.
Gebietsführer Kowarik also dealt with the issue, which shows how important it was taken at that time.
Finally, a quote from the SRD-Gebietsführer Hamburg on the completely different hairstyles:
"Wie die übrigen jungen Leute alle aussahen, mag schon die Tatsache zeigen, dass ich kurz nach meinem Eintritt hörte, wie jemand eine Gruppe warnte: 'Vorsicht, Gestapo und Gebiets-Streifendienst sind da. Erkennt ihr sofort, sehen typisch aus, kurzer Haarschnitt'."
"How the rest of the young people all looked may already be shown by the fact that shortly after I entered I heard someone warning a group: 'Watch out, Gestapo and
Gebiet Streifendienst are here. You'll recognise them immediately, they look typical, short haircuts'." (1940)