He's not shaken at all. Cause when you casually wipe out five of the strongest shinobi in the world, and are currently standing atop the monster to end all monsters, a monster who knocks away mountain-wrecking attack like a mote of dust, you aren't shaken.
Not to mention the guy can - and has - wiped out massive groups of shinobi as his 'I'm here' move... Yeah. I honestly give them about, oh, 5 seconds before he wipes them out. Less if he has Juubi blast them.