Propaganda? I don't follow.
She's saying that she would have taken her son to Canada had she known what she knows now about the war in Iraq. This isn't the same as the government deliberately spinning and manipulating facts to convince people of something. She's just expressing an opinion.
Presumably, her son didn't know this either when he enlisted, or the two of them would now be in Canada. So yes, he believed in the cause when he signed up to fight. But that's not what she's talking about: she's saying that
if she had known (and this applies to a lot of soldiers), she wouldn't have supported the war. After all, many soldiers signed up because Hussein posed a threat to the United States, and because he had weapons of mass destruction, right? Neither of these were the case.
Also, something tells that she wasn't making some subtle comparison to Vietnam when she said that she would have taken her son to Canada.