The key here is the very last few seconds when "S" started to round up. What did "P" do? If "P" jagged the stick and did an emergency bare away immediately after "S" changed course and a collision was still going to happen then I'd say "S" has fouled. If "P" delays by even a short time and then reacts or only a mild change of course then "P" will clearly have fouled. The devil is in the detail on this one.

As Eric says, the best thing is to avoid the situation in the first place.

Tiger Mike