Tesla can certainly bring it, but the internal combustion engine has over a century of demonstrated reliability.
Keeping in mind that electric cars have been around longer than gasoline cars, and than electric motors are used in the powertrain of every modern locomotive in the united states (and are the prime movers for almost any industrial plant)...not really, actually.
Car engines need a lot of maintenance due to all their sensors, electromechanical and mechanical valves, mazes of hoses and wiring (all of which has to deal with high temperatures), dependence on multiple fluid types (the fuel, the coolant, the lubricant) and need for so much cooling (gasoline engines waste 3/4 of their fuel on heat.) One of the reasons Tesla is getting away with not having dealers is that the cars are so much simpler drivetrain-wise. I imagine the only fluids that need changing are the brake fluid and probably the gearbox oil.
An electric car for the presidential limo would be brilliant, particularly since it typically doesn't need to travel very far most of the time, and an electric vehicle provides massive torque for handling the heft of all that chassis and armor. Adapting an electric drivetrain, in part because of how simple it is and how flexible one can be with component locations, would actually make it far easier on the coach builder. Tesla already has a dual-motor AWD drivetrain, so they've definitely got the oomph (although I suspect the dual-motor drivetrain motors are individually smaller.)