During that era, having Rosa Parks (and potentially many other men and women of color) in "the wrong seat" could have potentially diminished the attractiveness of taking that Bus line for the patrons, thus damaging the Bus Line's profitability.

A more modern example of the presence of something "unwanted" bringing upon "damages", is Walmart moving into a high end town (which from what I understand, leads to a decrease in property values).

I am playing devil's advocate here, but Rosa Parks certainly could harm the Montgomery Bus Line with her inaccurate seat occupation.