I have experienced scenes comparable to this more than once at the DUS B Gates. Not a good experience but I try to offer a bit of background information as a regular to DUS and to the Gate the OP was heading to.

Probably only.a few of the staff (close to none) at DUS B Gates are German, most are Turks or of ME origin. Most of the English native speakers head to the two non-Schengen gates for London bound flights. All other B gates are Schengen gates which tells a bit about the dominating language at the B Gates.

Quite frequently harsh discussions emerge as these agents do speak poor Englisch and several of our friends heading to B33 and B35 speak nothing but their native language. Staff their has a certain (cultural) attitude of loving to excercise power and quite a few travelers heading to the said gates have a certain (cultural) attitude of being snobby and expect everybody to speak their native language, an expectation they cannot take for granted. This sometimes provokes cultural clashes.

The OP, obviously trying even to invent an English race, appears to fit pretty well into this pattern of experience. And, true, being British myself, it does not take a aweful lot, to identify somebody as London bound or based at the DUS B Gates.