If you're implying that it's a silly idea, I agree with you.
The solar heating aspect of this is a distraction. Compared to the heat generated by rolling friction, I think it's probably negligible. But technically, if you had uneven tyre pressures to begin with and then drove with the higher pressure side facing the sun, the sun would make the imbalance that tiny bit worse.
Come on guys, nobody's saying you've been doing it wrong. People are just tinkering with ideas for making things better, if possible. There are some technical reasons why airing 2 or 4 tyres at a time can result in more even pressure distribution than doing them one at a time. At the same time, I keep saying it isn't a big deal...

