He's pretty hopeless with his default loadout. Needs time to summon his guns and pick them up. In a place like the beginning of Stowaways (Uncharted stage) he gets massacred.
Franzea and Stowaways wreck Emmett so bad its not even funny. But at least Stowaways opens up to a wide relatively even space after some time with easy to dodge hazards. If you can survive long enough inside the plane then you should be ok. Franzea constantly shifting stage just kills his level 1 sniping game if thats how you play as him.