A lot of people wanted to talk about this at the time, and the election result was after the training cutoff, so I’d guess they threw this in there to reduce waste due to hallucinations and/or web searches.

I have to imagine with the event occurring after its training cutoff, a question like "who's the president of the United States?" could have confidently returned a now-outdated answer. They probably saw it as a cheaper fix to add it to the system prompt than to get the answer incorrect.