Why the Pope seems like an automaton

Just watching his visit to Spain on TV I noticed (perhaps for the first time consciously) that the pope never moves his arms when he walks, which gives him a bot-like appearance.

The facial expression is also pretty fixed into that attempt at a benign smile that turns out more, you know, Darth Sidious.

A quick image search reveals plenty of pre-made comparisons. But is my arm movement observation fresh?... almost certainly not - I'm not gonna search that.