Can plasma physics establish a significant bound on long range dark matter interactions?

Dark matter has been theorized to be charged under its own "dark electromagnetism" (dark-EM). Under this hypothesis, dark matter can behave like a cold collisionless plasma of self-interacting dark matter particles, and exhibit plasma-like instabilities with observational consequences. Using the results published in [1], which studied the degree of slowdown between two interpenetrating $e^-\,e^+$ plasma clouds due to plasma instabilities, estimates of similar interactions for colliding "dark plasmas" are explored. Comparison with astronomical observations reveals strong new constraints on dark-EM with the dark electromagnetic self-interaction $\alpha_{D} < 4 \times 10^{-25}$.