‘That is not what the meaning was when that was written into the Massachusetts constitution. It was an after the fact effort to read into the words something that was never intended by the authors or those who approved the document”
And you know this how?
Many reasons, not the least of which it had to go through a Judicial circus to overturn it. If that had been the intent of the framers, it would have been announced, and there would have been no need for a court case. Additionally, if that had been the intent of the framers, there would have been a hue and cry from those slaveowners who would have seen this effort as a backdoor attempt at depriving them of their rightful "property" under the then existing English and Common law.
Also, if it had been the intent of the framers, they would have said so in clear and plain language rather than couching it in flowery prose meant to elevate themselves rather than to make slaves their equals.
You are lying to yourself if you believe this bit of verbiage was intended to free the slaves. It is important to realize that what we wish to be true, and what is actually true are not always the same thing.
Wishful dreaming in the interpretation of law is malfeasance.