Jan, The fact that Krishna represents 'Hinduism' and it has it roots in Vendanta might put off someone who don't accept immanence of God and Karma theory. That is the essence of BG, IMO. If someone can take the wisdom of BG irrespective of its roots then whether BG is hindu scripture or not really does not matter. If someone does not take BG because of its roots, well, they will be at loss. And BG is open to all, not exclusive to hindus, to accept BG as a guide but not to become a hindu is also an option.