Right but if mafia has two traitors, which is now very likely, they had limited opportunity to collaborate and wouldn't have been much likelier to bid well than town.
Sure. Except 2 Mafia and 2 Traitors is weak with a half-SK.
1 Traitor is the equivalent of 1/2 a Mafia usually - that is, in a setup where 3 Mafia might be too strong, 2.5 is within reason.
In a 17 person game with a Half-SK, "3" Mafia is too weak. I expect that the Mafia team consists of 3, with 2 Traitors.
That's 5 "Mafia Aligned", 1 Half-SK, 11 Town.
The only alternative is two Mafia factions, each with their own traitor - which would make 6 Mafia aligned players (2/1 for each faction), 1 Half SO, 10 Town - but we've seen nothing to support this theory.
Thus {3/2}/1/11 is probably accurate - and knowledge in 3 spots should be more than enough to secure a top 6 spot in 17 players. Randomness alone would be close enough to make the argument.