Government has just as much right to set it's purchasing criterial on the basis of what it deems valuable to it's business as anoyone else. You seem to be treating this as if they were setting a law for all businesses in the State.
Instead of being reactionary why not demonstrate how they are harming the state or squandering the citizens funds by their decision. This would be far more likely to convice government and world+dog.
Oh, and let's not be naive. If there was any possibility of success would not Microsoft seek the same thing. In that case the arguements against would be a little less philosophical