Of course it would be okay if he lucked into me, or loitered in a likely area. He played fair and won. Totally not cool for someone to be waiting because a spy told him where I was going in relatively defenseless planes. Why is the difference between the two scenarios not obvious?
Under the first scenario, you have an opponent to deal with. Under the second scenario, you also have an opponent to deal with. What difference does it make how he got there, and how do you know with certainty why he is there? It's an opponent. Fight it out with him.
Wiley.