Cap gave Scott an ultimatum. Regardless of whether Scott had refuted him verbally or blasted him, the result would have been the Avengers invading Utopia. Steve came armed and in uniform, not as a diplomat. He met them on a beach, not in their base. I don't think he came under a white flag. All indications were that the US government was demanding something immediately, and the Avengers leader was armed and ready to take it by force. It smacked of arrogance and high-handedness.
The Avengers are irrefutably an antagonistic force. The heroes were the X-Men, and by the end hardly any X-Men were in the moral right either. The Phoenix was not evil, and only corrupted after idiots attacked and broke it, much like Endsong. There are ways for utilizing the Phoenix for good and avoiding corruption. The US government should know better than to try $%^& with a cosmic force of destruction. Only a handful of X-Men had the knowledge to do that, and Logan knows jack-all about the Phoenix. This is all more or less Nick Lowe's position, which I will take any day over Breevort.