He'd just been attacked by a magical source that disarmed his weapons at the wrists, was cast wordlessly and without wand motions, and did not leave an obvious bolt to block. This is probably a bad time to show off.
At a deeper level, Voldemort (and Mad-Eye Moody) favor a combat philosophy of dodging, under the quite reasonable realization that there are a large number of spells that can overwhelm shields or are unblockable.
This is a new thread to discuss Eliezer Yudkowsky’s Harry Potter and the Methods of Rationality and anything related to it. This thread is intended for discussing chapter 114, and also, as a special case due to the exceptionally close posting times, chapter 115.
There is a site dedicated to the story at hpmor.com, which is now the place to go to find the authors notes and all sorts of other goodies. AdeleneDawner has kept an archive of Author’s Notes. (This goes up to the notes for chapter 76, and is now not updating. The authors notes from chapter 77 onwards are on hpmor.com.)