PBS and NPR have to deal with this issue every year and their solution is pretty simple. They report it as they would want to, mention that X Co sponsored them in the past/present, and don't take their advertising dollars for that piece.
There's a big difference between saying "this segment is sponsored by X Co" and letting X Co write their own endorsement that they can then quote as a testimonial from you.
If you're referring to Desk quoting Gruber on their home page, they quoted from Gruber's "thank you" post which, while it borrows a lot from the original sponsor-written post, is still written by Gruber himself.
