A single dp28 wouldn't run the risk of turning anything into exterminators, there is a reason you get a pair for only 75mu.
And a dp only makes them shittier ostroppen being more expensive troops with a worse weapon. All it does is change which unit they are most comparable to and worse than. Ultimately there is no reason for a clearly inferior unit that can't function alone nor work properly as a support unit to be priced the same as units that can.
The idea of giving Conscripts a single DP-28 was brought up before. Miragefla and Mr. Smith turned the idea down, because then we would have DP-28 Conscript blobs that are essentially just as lethal as any LMG42 Grenadier, LMG34 Obersoldaten, M1919A6 Riflemen, or M1919A6 Paratrooper blob (just use quantity to overcome quality) but more durable, have a Molotov, have an AT snare, cheap to reinforce, and can Oorah away from or around HMGs.
I would argue that the LMG42 upgrade for Osttruppen is acceptable because they receive a 50% accuracy penalty outside cover, making it worse than a single DP-28 outside of cover.