
After talking to you he swims directly off, no matter if the water has been cleared of Lakelurks or not.
He will appear on the Scavenger Platform if you wait long enough. If you've waited 24 hours, your waiting will stop and he'll be there to talk to you. Sometimes he can be encountered to follow you in Yangtze Memorial and if you wait in Primm, you'll encounter him there as well. Malcolm seems to follow the player after a set amount time after you leave Goodsprings. Malcolm is carrying the roving trader hat and roving trader outfit both of which are valuable for players to increase their trade profit and pass Barter checks at the lower levels where one is likely to encounter Holmes. That simply might be all the Stars he found while he was collecting them. Malcolm claims he stopped collecting Sunset Sarsaparilla Stars a long time ago, yet he will still be in possession of 6 Stars. There is no karma loss if killed in stealth mode. Since he has 6 or 7 star caps on him, one should try pickpocketing or killing him after the conversation ends. He will disappear from the game once he arrives there. After speaking with the player, Malcolm Holmes will walk directly to the Mojave Outpost.