Don't think it will be good to set a param here. Would be nice if the layout could be used by other extensions as it is without overriding. Now we would be forced to override it simply because we don't have an article view and need to override the check and provide our own.
Imho that param should be set by the view (com_content/article view in this case) and then the plugin would work extension agnostic. As long as the extension follows the naming of parameters and row properties.