Perhaps he thinks Locke will end the war, or maybe it is that Locke has create his own destiny. Or possibly something else. But, for whatever unknown reason, Richard is waiting for Locke. In '77, Richard is "currently" helping Jack bring a bomb to a place where they can detonate it and stop the Swan from being built, in order to help Eloise save her son (and possibly stop the DI). But Richard has been preparing for the arrival of John Locke a long time. If Jack says one word about why he's trying to prevent the construction of the Swan - to stop flight 815 crashing on the Island, which would, in essence, result in Locke never having arrived there in the first place - Richard will not only stop helping him, but turn on him, possibly causing the Incident himself.