I think that Timo was thinking about a Von Neuman machine or a Turing engine. Such a 'replicator' would need a seed pattern to serve as a template. Modern CND still needs a model, a "design template" in order to fabricate.
Nope, simpler than that. The OP suggested that Geordi's lamenting the lack of antimatter aboard the
Hathaway meant that the stuff couldn't be replicated by
Hathaway's replicators because replicators cannot do that sort of stuff. But it's much simpler to assume that the ship's replicators couldn't create antimatter for Geordi because they didn't have enough fuel - the ship didn't have enough fuel. And the fuel, of course, is the selfsame antimatter.