I think that's an overly punitive assessment on the meaning of a 6 INT. Assuming the usual "3d6 describes the bell curve of distribution across the normal population" that simulationist-types prefer, 6 INT is someone at the top of the bottom 5% in intelligence. Almost certainly uncurious and easily persuaded, but definitely not at the point of not being able to tell friend from foe.
6 Str is your standard sedentary type that doesn't work out, or on the small side, not someone physically crippled.