Changing diapers where people are eating is a pretty gross. Lots of germs and always the potential for the little tyke to have an unforseen event sans diaper. It's nice to hear that the parent was at least trying to be discrete. I've seen parents change kids on the eating surface. However, they should find a bathroom or an area away from where people are eating to take care of business.
As for public breastfeeding, no problem with it what so ever. It's a natural thing. As long as it's discrete, what's the big deal. I'm more bothered by mothers that do breastfeed in public and then ask men to move away because they feel uncomfortable. I have a friend's wife that does this and it irritates me to no end.