However, a company's name mistakingly placed on a list of entities for or against any bill shouldn't equate to slander.
It isn't about someone mistakenly putting a name on the list, it is about someone purposefully putting a name on the list. Slander is when you say something you know is not true. Someone could spend all day putting Slashdot on that list and X amount of people are going to see it. Some will eventually learn the truth, but there will always be those who forever think Slashdot supported SOPA.
2 very different games, I don't understand why people compare them in the first place.
Yeah, it would be like comparing Apples and Microsofts.
The decision doesn't have to be logical; it was unanimous.