UV light does not just create repairable dimers in DNA bases, it can and does rip DNA apart. Enough exposure would cause more than enough irreparable damage to kill the cell and 99% of the cell being destroyed is certainly not salvageable.
The Delta flight is cheaper. But check a bag at a cost of $25 for the first checked bag each way on Delta, and your total fare climbs to $256 -- more than the cost of the Southwest flight, which includes free first and second checked bags. Add a second checked bag for $35 each way on the Delta flight, and you'll pay a whopping $326.
JetBlue Airlines. JetBlue, while not totally free, does offer some free baggage options for domestic flights. JetBlue baggage policy includes one checked bag free of charge. A second checked bag is allowed for a fee of $30 and a third bag for $75.