The techdirt article points this out too. When there's a law up for debate which a client wants to get through they try to get these letters in to make it more likely the law will pass. And yes this is different from official "support" which is saying "we the law firm want this law to pass." This is more like "our lawyer looked at this for our client and he does not think it's unconstitutional though this is not the position of the entire firm." To me, that's still bad but I completely understand if others are okay with it. Reasonable men can and do disagree about a lot of things.
Is it really wise to get in bed with ESPN in the first place? that's all I'm saying. I am not and will not be the first to argue that sharing lawyers with those on opposite sides of important legislation with you is a bad idea.