No, he isn't. The words are simple and straightforward.
He says explicitly that it is not necessary that a man should be born in the country to be a NATURAL BORN CITIZEN.
The "grandfather clause" exception has nothing to do with NATURAL BORN CITIZENS.
So he is clearly not referring to people who were covered by the grandfather clause.
Because such people, BY DEFINITION, WERE NOT natural born citizens.
Initially, until the children who were born of citizens had reached 35 yo, there were no Natural Born Citizens, by definition. How could there be?
We've been over this birther myth several times already as well, although you may have missed it. For an extensive discussion of this myth, see for example here, and here.
It essentially restates the idea that being born in country to citizens is what makes you a NBC, just like the exception does.
Read it again. It clearly says that you don't have to be born in the country to be a natural born citizen. You only have to be a citizen by birth.
Chief Justice John Marshall, legendary Supreme Court Justice Joseph Story, and famed judge and legal expert Chancellor James Kent, as well as "other distinguished jurists," all agreed with this statement that it DOES NOT take birth on US soil plus citizen parents to be a natural born citizen.
Being a CITIZEN BY BIRTH is enough.
The fact that the exception is there, written as it is, should be enough to show you your error, since it further supports the definition by being the exception to it, see?
It is, as the FFs might say, self evident. Your quoted material, though not clearly written for us now, is telling you this as well, while explaining some of the reasoning behind their intentions.
When you have several opposing opinions, answers can be found, not by a battle of opposing quotes as is your way, but from determining intent and purpose, and then letting the facts tell you the truth.
Letting your agenda dictate your truth first, then cherry picking your facts and ignoring inconvenient counter data, is the wrong approach and almost always results in error.
Global warming is yet another of many such examples from your team's playbook.
To find the truth, it's better to be a trouble shooter, an engineer or a forensic detective, rather than a quote hunter, and let facts and your reason tell you the story and show you what the truth is.