I think that in order for something to be considered “safek pikuach nefesh” on Shabbos, there has to be a reasonable level of “safek”. Otherwise, just about anything would be allowed on Shabbos.
I was once at a Shabbos Seudah where this was being discussed. The question was “what is the level of safek that would constitute a “safek pikuach nefesh halachically?” I don’t know the answer to that question, but there is no way that your situation would constitute a “safek pikuach nefesh” since there is absolutely no reason to assume that the person in question would need medical care on Shabbos or that he has necessary documents in his wallet (and this is even without Joseph’s post that he wouldn’t need it anyhow).