I think either Scout, Pyro or Soldier are not in the game. Doc unintentionally left us a hint with his dying message, saying that he "knows his scumbud
s can pull through". Since every town role is doubled, that can only mean that there's four scum in total, because it wouldn't add up otherwise.
Out of those three TF2 roles, I think the Scout is the Commuter. According to the TF2 wiki Scouts are the fastest units in the game and can dodge projectiles. If Toxic is correct in assuming that there's a Jack of All Trades in the game, that would likely be the Soldier, who's described as being versatile. The Pyro is likely the one role not included, because there are no Arsonists in this game.
The question now is wether
@Toxic_Snowman is correct or not. I'd like to hear where this idea of his is coming from. Were you subtly softclaiming, or is it just a hunch?