I think the debate of whether or not actions can be *totally* selfless or not isn't very relevant outside of church or philosophy class (like I said... church). But actions have a greater or lesser degree of selflessness. I really think attempting to reduce all human behavior down to economic calculations is kind of absurd. If the presumably selgiraffe motivations of the subway guy were his primary motivation, then nobody else on that platform could have been similarly motivated by checks and fame, or else they'd have done the same thing, right? Do you really not think it's possible that in the second or two he had to act, his thoughts were simply "oh shit! that guy needs help!" And yeah, afterwards he got his, but that's like saying heroic soldiers only do it for the medals. That's bullcrap.
I would call them "selgiraffe" motivations. Maybe egoist, but not selgiraffe. Yes, they don't save each other's lives for medals, but they do do it for a reason. Egoists believe that the reason would be that they like their friends, and if they die, sadness would ensue.
See how Philippe refused to let his ego be fed? That was to feed his ego. That was to reassure himself that he is a good person.
I don't know if psychological egoism is true. Wikipedia says something about science proving it isn't true. *shrug*
But anyway, I think you can reduce all human behaviors to calculations; consciousness does not transcend the laws of the Universe. I don't really see why it would. Yes, a person can rebel if someone predicts that person will behave in a certain way, but that was because you just provided extra stimulus (predicting what the person would do and telling him.)
You should read Notes From Underground.