Thats right, but one additional level of depth in fetching repositories increases the API latency by so much that almost becomes unusable for a web app at least for a hobby web app :P Hence the shortcuts. Open to ideas and suggestions.
As I said, your approach is a clever way to use the GitHub API. I think you need to change the title and readme to indicate that this isn't an LDA index of GitHub descriptions. To ML practitioners, that's what you are implying with a title of "Show HN: Using LDA to suggest GitHub repositories based on what you have starred".