You can't tell anything by looking at a picture.
You need to know the details behind the picture such as did she purposefully dress up ViVi like that to take her picture so that she could post it on her blog with a statement about war etc.
Now if she had done that, then yes, I would say she is using her child to make a political statement.
However, according to what I've been reading that is not what happened. So IMHO she's not using her child. She simply posted a picture of her on her blog playing "soldier". This isn't the first picture she's posted on her blog of her kids. There are dozens and dozens of pictures of her kids and wife on her website. If that had been a picture of her with a barbie doll, no one would have batted an eye.
It just so happens that people consider Rosie contraversial and choose to read all kinds of things into everything that she does