> are they going to be more noteworthy for their scholarly work or for their strong political opinions
Swain researches the "representation of African Americans in Congress." Gay's work was "on black congressional representation, electoral districting and descriptive representation." Any work on those questions will require voicing politican opinions; the work is deeply political.
Most people interested enough in politics to do political research are likely to also be politically active. However, it would be possible to do political academic research detached from one's personal politics. Similarly, most biblical scholars are religious, but there are notable atheists among them.
You don't need to be politically active to do political research and you don't need to be religious to do religious research. Though, the correlation in both cases is likely high.
Swain researches the "representation of African Americans in Congress." Gay's work was "on black congressional representation, electoral districting and descriptive representation." Any work on those questions will require voicing politican opinions; the work is deeply political.