Re: Muawiya Sahab
Simply being alive during the time of the Prophet doesn’t give you some automatic near infallibility protection (did it ever for the times of prophets before that time? what does the book of Allah say about the Banu Israel during the time of Musa for instance?), nor does being a wife of the Prophet guarantee that you are above criticism (what does the Quran say about the wives of Lut and Nuh ?), so every individual is held to account for their own deeds. This is as true then as it is now. If any individual or group within the Sahaba did wrong then they were rebuked by Prophet saww. There are many examples in the Quran itself. The concept of see-nothing say-nothing idea does not make sense at all.
Prophet Mohammad’s stature unparalleled to anybody so your comparision is invalid. Every Muslim must believe that each word and act of the Prophet is by the approval of God.