Is It EVER OK to Do This on Metro Bus/Rail? [POLL]

This happened to me last week...

..I was on a Metro Bus, headed home from a late-morning staff meeting. The bus was fairly crowded, so I was forced to sit all the way in the back [which I hate, because you have to climb up the stairs, and it's awkward to do that while the bus is moving].

Anyway, a few stops after me, a young man got on board with his two young children [I don't think their combined age was 8], and sat next to me in the back row of seats. I must say that he was doing his best to keep them from standing up or moving around the back of the bus.

A few minutes passed. I had just picked up my Kindle when I got a whiff of...well, let's call it Number Two. Now, I'm not overly sensitive to things like that. But for some reason, I turned my head, in the general direction of the odor. What do I see but the father changing one of his kids' diaper on the last seat of the last row of the bus [and, incidentally, two seats over from where I was]?

My first concern was that, if the bus had to stop suddenly, the poor child could take a rough fall off the seat. Then, I started thinking about my own health. Many illnessess are airborne, and the wind was blowing through the bus' open windows. If the child had anything contagious, he might share it with a few of his fellow passengers. And let's not even discuss how the more sensitive on the bus might think about such an act!

To top it all off, the young man threw the diaper out the open bus window! If it hits the side of your car, it's messy, but could be washed off. But what if hits your windshield?

Again, to give credit where it's due, the young man was very apologetic about the whole thing. But still, it just seemed totally wrong to do on public transportation. The results of my unscientific research [asking a few moms if they would do such a thing. They all said no] seems to indicate diaper changing on Metro Bus/Rail is a big no-no.

But I might have asked the wrong people. So, I'm asking you: