I won’t claim to be an expert, but I doubt a person can test positive within a few hours of being exposed to the virus. Takes time for the viral load to grow high enough to identify on the tests. IOW, probably did not get covid from this event. Possibly spread it to others at the event, maybe, but we don’t know the level of interaction this person had with others. From the videos I saw, nobody at the diplomatic level - not even the President, Prime Minister and Foreign Ministers - shook anybody’s hand and they maintained distance.
If you ever do shake someone’s hand, it’s not a big deal. You can always go wash up with soap and water soon after. Just excuse yourself to the restroom.
More importantly they wore a mask, nobody can get the virus if they wear a mask, the mask is the cure, just wear the damn mask.