Saying "making it illegal to use illegally-gained funds is something I suspect most US citizens would be OK with", is making an argument that the law is good in the eyes of US society, even if it doesn't state your specific position.
But we aren't starting from a position of knowing that a majority of society agrees, which is my point. If you state that you don't know much about x, so have no opinion, but believe that most reasonable people believe y about it, then you still are stating an opinion about x, even if you are doing it at one level removed by saying what you think other people might think.
I think that a majority of society thinks about law and order through an entirely simplified lens, and would see such a law through said lens without considering the actual implications of it. The idea that "money came from bad people doing bad things, so we should punish them" being the only really "logic" here.
Much in the same way that you can skew poll results based on the way that you phrase a question. For example, years ago there was a poll about whether or not people wanted ala carte cable channels. The question they were asked was, "Do you want more choice or less choice in cable programming?" Obviously people want more choice, but this answer was associated (by the pollsters) as being against ala carte options for cable.
