Sister wouldn't be in such a hurry to discount this paper's findings out of hand.

If endlessness ran NMR on the DCM from an acacia extraction, would the chlorinated product even show up? The paper above implies it would not be soluble in DCM, and would have fallen out of solution. Its also very possible, due to the trace amounts of alkaloids in acacia to begin with, that any precipitated chlorinated product might have been overlooked by Endlessness. 

Sister has also seen similar references over the years and would suggest that using DCM for a quick extraction would be fine, but prolonged exposure to it should be avoided. But as DCM is not very selective it wouldn't be Sister's first choice as an extraction solvent anyway.