He probably should have been armed with some more one liners. He had a pretty good one for the 47% attack - equating it to Biden’s gaffes.
Biden is a real shark though, and has been debating and arguing before Ryan was even in diapers. There would have been a real danger to attempt a toe to toe exchange, with little upside other than our visceral pleasure.
The important thing is he walked away without any gaffes, or Dan Quayle “deer in the headlights” type of moment. This allows the campaign to return to the Romney momentum story.
I also think this play it safe strategy by Ryan and Biden’s hyper aggressiveness shows that both campaigns believe that Romney truly is ahead and it isn’t just some debate bounce polling aberration.