How can it not be a tax when it says right there in the text that it's an excise tax?
You are citing the wrong part of the Act.
The individual mandate everyone is arguing about and which Roberts ruled is a tax is in §5000A.
You cited what people call the “cadillac” tax in §49801, which is not the individual mandate but a different provision entirely.
But don’t feel bad, Congress didn’t understand the Act and they actually voted on it!