Spider-Man is a killer now. It doesn't matter if Doc Ock won or the fact Doc Ock was about to die in a few minutes, because the way Peter saw it was he deliberately tired to kill Doc Ock.
Peter even says pretty much word for word that he crossed a line he said he never would. It doesn't matter how we see it only matters how he sees it, and he sees it as him killing someone. No one really talked about or noticed this when 700 came out because of Slott's sloppy writing and how busy everyone was feeling disappointed about the end of 700, but in all honestly this is and SHOULD be a big deal for Peter. I really hope that if Marvel doesn't retcon/reboot Spider-man to ink out all of superior that they don't just ignore this.
This could actually be very impactful to Peter. I mean if he can learn to live with the guilt of killing someone then he could start killing people when they need to be killed.