Would a character with unarmoured defense benefit from a shield?

@JeremyECrawford would a player with unarmoured defence benefit from a shield?

— Anthony Keen (@Antyface) April 1, 2016

Barbarian's Unarmored Defense: a shield works (PH, 48). Monk's Unarmored Defense: no shield (PH, 78). #DnD https://t.co/aclmULxVuG

— Jeremy Crawford (@JeremyECrawford) April 4, 2016