It's not that it's a MX base, it's that it's not a Hub.
Outstations feed passengers to the hubs, where they then fly to other locations. To get the passengers to the Hub 8-9AM morning departure bank the outstation needs to leave before 6AM to allow connections.
On the backside the regional feed takes passengers to the outstations from the HUB 8-9PM evening arrival bank and departs after 10PM.
It's not that it's a MX base causing the early departure, late arrival, it's that MX bases are put where relatively lots of airplanes are going to sit overnight. Causation vs Correlation.