According to director Joe Pevney, the network did have a problem with the line and the use of the word. He said Roddenberry fought for it to remain as no other word would "convey the emotion of the moment." He also said Shatner fought to keep it, that everyone wanted it to remain. The network finally relented. (These Are the Voyages: TOS Season 1 - Marc Cushman, etc. 2nd edition page 586). I couldn't find any audience reaction.