I think you are reading too much into the simple line which was meant to sound logical, it was supposed to be Spock's justification for noble self sacrifice to save his comrades and friends. Those friends later went back for Spock and told him they had too because the needs of the one was more important to them than their own needs, this too was meant to be noble. I don't think you should get too much into the negative aspects of Spock's line because you are forgetting that it is just a movie and not a lesson in a class of philosophy. Spock was a noble and intelligent character with no fascist connotations implied to what he did in the Trek movies and show. He was also meant to be depicted as a wise character who was explaining his reasons for his actions and decisions, it was meant to make him look good.
