"Publicly refer to" means in recorded speech (so not a written press release/statement likely written by someone else), but it need not be part of a formal address (i.e. bringing it up in response to a reporter's question or at a campaign event is sufficient to resolve yes).

Examples of specific AI models: "ChatGPT," "GPT-4," "Chinchilla," "DALLE-3," "AlphaGo." Mentioning an AI company and referring to its "product" or some such is not sufficient.

Mispronunciations where its clear he intended to refer to a known model (i.e. "GTP-4") will resolve yes.

If a reporter asks something like "what do you think of GPT-5?" and Biden responds without repeating the name or otherwise demonstrating it's something he's specifically aware of, that is not sufficient. Repeating the name in perfunctory way that suggests no previous private discussion/thought about the model is not sufficient in principle, but presents a hard edge case that will resolve with my best judgment as to whether previous thought/discussion happened.