Exactly. The ones that "care" what the source is are the ones who just want to believe what they want to believe, regardless of facts. The MO is always the same: "anything that confirms what I want to believe is correct and anything that does the opposite I will try to discard with even the weakest argument there is until the very end."
There is nothing wrong with eventually using the source in an argument, but if the person does ONLY that and does not refute what is being asserted, you know that person is full of shit.
As always, "the worst blind man is the one that doesn't want to see."