Don't throw your pearls before swine. They will misspend the money in rage and then come at you with drooling fangs and glowing red eyes.
If the nation is being invaded and laws prevent the President from defending the country, then his oath compels him to ignore Congress and follow the constitutional guarantee at the border. How else can he preserve, protect, and defend the Constitution? The oath implies action outside of the written statutes. Simple vetos don't fit the notion.