the sentences U: "The enemy is now approaching." and V: "The enemy [is] approaching simultaneously with U." are presumably made true by one and the same fact -- the tenseless fact of the enemy's approaching at some time t which is also U's time of utterance -- despite their lack of synonymity.
So the inference from language to reality seems thoroughly unmotivated. (Am I missing something?)
One way to bring this out is to consider the analogy between 'now' and other indexicals, e.g. 'I'. As Lewis and others have pointed out, there seems something special about attitudes de se, which refer to oneself under the indexical guise. They cannot simply be paraphrased into objective worldly descriptions. But I take it no-one is thus tempted to infer that the world itself contains a special property of "I-ness", held by me alone. So why does tensed talk tempt anyone into inferring that the world itself contains a special property of "presentness", held by the current moment alone?