I suppose that what is meant is the right words, not just the number. The autogenerated ones would not be intelligible Lojban, even if they were well-formed.
The claim is basically, that we aren't "finished" because we haven't talked enough about enough things, certainly that there are things talked about in other languages which have never been mentioned in Lojban and yet are in the realm of Lojbanists' experiences (this to keep Piranha finished even though no one has talked about nuclear physics -- or plain physics -- in it).