On the flip side, the WSJ could say the exact same thing about Google, Facebook, Ars Technica, etc. Just because they offer a different viewpoint doesn't mean you should completely write them off. Instead, it is useful to read these types of pieces to see what the opposition really wants.
If there is to be any sort of compromise, we can't just shut our eyes and plug our ears when the traditional media says what it needs in a law.
There is a difference. Google and Facebook are not media organizations and are clearly stating that SOPA will hurt them. People go to media companies for news, and when they see op-eds like the one in the WSJ, are less likely to consider that the writer herself is a critically invested party in the issue.
It is not the same thing for Reddit/Ars Technica/Google/others. It would be the same when Reddit/Ars Technica/Google/others sponsor a bill to cut the electricity of the printing press of any newspapers when suspected of copyright infringement. In that case WSJ can claim whatever these sponsoring companies said are propaganda.
If there is to be any sort of compromise, we can't just shut our eyes and plug our ears when the traditional media says what it needs in a law.