Being nice to foids actually makes a lot of sense. Think about it, as an incel your interaction with women is meant deceive her into thinking you are a bluepilled cuck, so you can secretly use blackpilled vengeance to sabotage and destroy her. If she had ANY ounce of thought that you don't like her she would put up a lot of defenses. As a low smv person that would make you unthreatening. Of course this is meant for with you're stuck in a social setting with a foid in a woke environment.
In movies usually the extremely violent serial killer is the nicest person of all since they rely on secrecy and deception. Niceness is traditionally the Hallmark of extreme evil, and the greatest supervillains are the nicest, stabbing people to death with a pleasant smile. There's nothing cucked about weaponized niceness.
Being mean to foids is only useful to normies and chads since that gives them the possibility of sex. To an incel being mean to foids doesn't have any positive.
That being said there are some cultures that promote meanness and hate niceness such as hood culture in which case you'd have to be mean to blend in. It's basically a 'based' culture since they want to reduce the extreme deception of niceness.
It's not good to take the advice of the autistic foid. don't generalize it since you already know how nice you need to be to everyone. If people actually liked you they would tell you to be less nice to them. So for example you could be less nice to this foid but by being neutral and nonchalant and equinamous instead of nice and not by actually being mean. Usually being nice is how you talk to people who hate you.