Let's say the authors did intend it as you say. Did the representatives voting on it understand that when it said what it said, it really meant something else? How about the people who decided whether to call their reps in support or opposition? How about the citizens and companies planning to comply with the law: did they know that what it said wasn't really what the authors meant?
Do you see the problem here? There is a legitimate enough debate for this to make it to SCOTUS and you're saying we should let it go because obviously the authors meant it that way.
Except John Gruber is on video explaining how the states who try to stop Obamacare by refusing to set up an exchange will get pummeled by the people who realize they are paying taxes for Obamacare but are not eligible for any of the tax credits because their dumb Republican governor played politics and didn't set up a state exchange.
So what really happened here is revisionism after the fact, at worst, and definitely no consensus amongst authors, reps voting, and the citizens deciding on support.