Mosquera's preference for the right foot didn't seem to impact his performance on the left side much, nor did it apparently disqualify him from being picked by Arteta.
Burnwinter I think that's a thing that summarised Arteta as a player too; he was just a lovely midfielder to have around. He made standing tackles, as opposed to say Flamini who was always rolling around in the mud. He held his position as the pivot instead of chasing back on every runner because the idea was that being proactive was more important than being reactive.