It's an unfortunate disagreement. In my opinion, the constituents behind the prospective lawsuit want the Crenshaw line to be a subway, as opposed to at-grade. Other's are adamant about having a station stop at Leimart Park (which is a good idea)...but Metro's Board didn't resolve all of their concerns via the community outreach process, and now the community group (led by the woman that was fighting for Bernard Park's council seat) is using CEQA to leverage more 'play' with regards to their negotiation tactics.
Lawsuits, in my opinion, divert money away from design and planning, and inevitably compromise the project. If we could inspire a more diligent community outreach process as led by architects, then I'd hope that these types of disagreements could be ameliorated in advance before going to the courts.
Also, I think there is an opportunity for architects to demonstrate to communities that, if designed well, at-grade light-rail is a much more desirable transit system (especially from a user's experience) and from the POV for return on investment for the community. Subways are hidden and don't necessarily add anything of merit to a neighborhood as compared to a well-designed at-grade or above-grade physically inspiring presence.
That's my two cents.