The unps should have stopped play right away when they saw Happ go down. However, the fact that they didnt definitly means that the Rays players should have stopped playing; however as you already said, it may have been human instinct. On the other hand, human insticts should have also kicked in, and they should of tried to help Happ. The important thing though is that the trainers are able to get out as soon as they can, THIS is why play should have stopped, so the trainers could get out on the field quicker. Of course though, as you also already said, you cant play the Rays players, seeing how concerned they were afterwards. I really dont think those two runs should have counted since there was a serious health risk on the line, but once again, the Rays players just did as they are paid to do, and showed sympathy after. Luckily, the trainers got there in time and hr should be all right- he has been released from the hostpital.
When something like this happens, there is many different opionions. One person may say keep playing, its their job, and its a good oppertunity to score (I personaly think that is horrible), and some people will say that this goes above the priorety of winning, since it will impact his life for ever (I think helping him over winning is the right thing to do), and in a time when something like that happens, they all most come together.