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.
No man is an island if he's on at least one mailing list.