When the flashbang went off, Bridget's armor tried to react.  Armor was designed to work in both space and on the ground, so the pressure wasn't as effective against her as they used to be, but that's also why they packed more power.  The flash she partially mitigated by looking away and clenching her eyes shut.  However, she was still disoriented for several crucial seconds as she tried to regain her wits.