All it means is that is where you start and end your tour. At a fractional, when you go to work, you are assigned a tail number generally for the entire week. You go where they schedule the airplane to go. At the end of the week they fly you back to your base from where ever they plan to do the crew swap. It doesn't matter if it is one of 5 bases or one of 100 bases.
Fractionals, by nature, do not really have "bases" in sense that airlines do. We don't know very far in advance where we are going the next day. Heck, the sat-phone rings and changes the plan as we are flying A-B and makes it A-C or A-D even.
EXTW