No. A General officer shouldn't go directly from the military into politics. It's a little too close to the "man on a horse" phenomenon. I have immense respect for the military, but we should be very careful about breaking down the separation between the military and civilian side of government.
I have immense respect for the military, but we should be careful about. If he's politically inclined, let him do something in the civilian world for a few years first, as Eisenhower and others have done.
And besides, one afternoon's performance on Capitol Hill is a pretty slender reed to form an opinion of whether he's suited for political office. He may be a Democrat for all anyone knows. Not cracking on Casey here, he may be a fine man. It's just WAY premature to be talking abou this.