Almost always, the Wednesday before Thanksgiving has an accelerated academic schedule. The first period starts at 0655, second at 0755, etc., without a break for lunch so sixth period ends at 1245. Mids are allowed to leave immediately after their last class or obligation (LMO), so if they don't have a fifth or sixth they can take off early.
The trip to BWI is about 20 minutes (without traffic). Security is usually quick...I've shown up with about 45 minutes until my flight and been fine.
If they do have a sixth, any flight after 1500 should be okay.
For the way back, keep in mind that EOL is usually 1800 that Sunday. The rule of thumb in the past was that flights coming back should be scheduled for at least four hours before EOL in case of delays. Obviously it's more than possible to make it back with a flight that gets into BWI after 1400, but if it got delayed and the mid missed EOL formation, they could face conduct action.