The adult comparison doesn't really work. You could say if the adult was genuinely upset then a bit of comfort would help. One could also say that if an adult was just a big sook having a bit of a non-eventful whinge....and everyone pandered to them, that adult would continue to be a sooky-la-la for the rest of their life.
It really depends on the specific situation: type of cry, length of cry, etc. In this situation I'm sure the mum will work it out and do what's best.