I honestly doubt he was even looking at dark pact. The enemy team simply wasn't showing on the map for a very long time; they aren't showing on lanes (except earth spirit) so they have to either be 1) jungling their neturals 2) smoked/trying to make a pick-of happen.

Because they are so far behind, jungling is not an option. This is high MMR pubs, and they know the only choice they have is to make a pick-off on a high value target and the only place on the map they can be is in their jungle which is why he expects the RP. People are over analyzing thinking he's looking at his passive; this is just game sense and understanding what plays are viable based on the game.