I don't really understand the dev putting so many suspicion points on the sister-in-law event anyway. Isn't it supposed to be kept secret? If so, how could he be suspect to the brother?
I know, I know.... stop trying to make sense of a f*cking game!
As kind of a developer myself (no game yet at current time, RL keep me too busy to focus on it, so no plans to publish here...
yet) I think, I kind got the point.
It's not more about the game sense, but more about you the player, its a form of brakes, if you don't cheat you have to administer the time more properly, with every current action generating high suspicion you need to balance work, lowering suspicion and corrupting the women all at the same time.
Sure cheating makes a lot more easy (my case for example), but if you take the persepective of a "no cheat game" you get to understand why the dev might have done that,
or maybe I'm just reading to much into it, take my opinion with a pinch of salt and you are good to go.