Not any more than Reuters should answer for what The Washington Times prints in its pages.

NPR sells their syndicated programming to this station. The realm of public broadcasting takes the concept of local editorial control very seriously, and no station is forced to do anything by NPR.

If anything, you may want to contact the WAMU advertisers who helped pay for whichever segment it aired in. Since NPR is selling content to WAMU and not buying advertising, I'd tend to think NPR would have much less leverage than the sponsors.