As one non-profit to another, I suspect the affected PBS stations are not concerned at all that Locast is redistributing their programming...
I seem to recall that the early episodes are public domain now?They might care about certain things that are licensed - in Iowa PBS stations run old Doctor Who episodes late Saturday night, the rights owner (BBC I guess, unless they have sublicensed it in the US) might have a problem with Locast even if the PBS stations themselves don't.