Don't worry about the flat tire rule! This has nothing to do with that. As I understand it, WN's flat tire rule is an unofficial courtesy extended at the airport. Most all airlines offer this, regardless of what any sort of paper or contract says.
No airline wants to come right out and publish the unofficial flat tire rule on its web site, because it would encourage droves of people to figure out that they can show up late for a flight and get on the next one.
Most (95%) of flyers are very nervous about the flying experience, most "normal people" are completely outside their element and in a discomfort zone at the airport. Most people fear missing their flight, and have no idea what an airline would do if they missed their flight. By not publishing the unofficial flat tire rule, you encourage the consumer behavior of arriving on time and figuring bad things will happen if you miss your flight.
If an ordinary consumer misses their flight and gets reaccommodated on the next flight its "the nice gate agent," not the flat tire rule. They got lucky, they smiled, they flirted, they cried, they did whatever, they charmed, there baby cried, they told them they had to go to a funeral the day after their wedding, whatever.
Also as far as this re-use fee, it will quite likely make the adjustment on the ticket in an overnight batch IT process, well after the flat tire rule would come in to play.
For example, in theory, on JetBlue if you miss your flight, you forfit any and all remaining value on the ticket. In reality, the airport generally accommodates pax under what we might call an unofficial flat tire rule. JetBlue's Sabre implimentation does not void out the funds until at least after midnight on the original travel date.
They can't instantly muck up (void or change) ticket coupons because they would cause issues with IRROPS if they literally did it the second the gate agent closed out the flight.
Again, JetBlue has no official externally published flat tire rule, but the airport uses one at its discretion. The call center, like any other airline, more closely folllows written procedures & contracts to the letter. You might get 4 different answers from 3 different agents at the airport about JetBlue's double secret unofficial flat tire rule. Or Southwest's for that matter.
Also with any airline an agent has the final discretion and the power if you will to do anything with you regardless of the rules. It is just what you individually can or cannot negotiate with the agent, or maybe the next agent. What you can or cannot negotiate is a lot more important than some contract that no "normal" customer reads.
