The militia is strong against inns, cellars, and warehouses and also has handy +2 coins, very handy if you're using your inns to play your actions more often. The militia is weak against watchtowers and libraries but the opponent actually needs to draw an inn for +2 actions with the library/watchtower to get anything going in an action heavy deck. Warehouse then watchtower is only good in a deck with good treasures.
Your opponent also managed to skip silver entirely and have +coin actions and gold in his deck. This is excellent when playing with warehouses and inns.