Is it true that enlightenment is equivalent with perfect knowledge?

It seems to me that there is a popular and strong belief that if you reach enlightenment, and thus have [four immeasurables](https://en.wikipedia.org/wiki/Brahmavihara "Brahmavihara - Wikipedia"), you can help a person without making them feel extra suffering or fighting back. This can be illustrated by the sutta [Aṅgulimāla](https://en.wikipedia.org/wiki/A%E1%B9%85gulim%C4%81la "Aṅgulimāla - Wikipedia"). The Buddha can stop him easily and effortlessly. The premise here is that enlightenment = perfect knowledge, and/or four immeasurables = you and the others are truly the same, so that you can understand that person inside out. The equal sign = is more like implies that rather exactly means. However, realistically, I think this is impossible. There are situations that achieving enlightenment does not mean perfect knowledge. For example, you can reach enlightenment in a radioactive region. This is not loving-kindness yourself. Likewise, one can never claim to perfectly understand the inner state of the other person, especially without face-to-face conversation. What it seems to be true is that enlightenment = having no distortion, and/or four immeasurables = being able to vision a way to help the others getting out of their suffering. Perhaps this is just a matter of defining what enlightenment is. This is fine. But in this case, its necessary consequence is that no human can achieve this state (though can absolutely achieve [mindfulness](https://en.wikipedia.org/wiki/Mindfulness "Mindfulness - Wikipedia") or practice eightfold path). Is this correct?