OT or not that is interesting. Could you expand your thoughts on this a bit?
I didn't see your question until now, sorry.

I'm not sure what new insight I can give, but let me try to express it (sorry if this is long, i might repeat myself)
What I was thinking is that numbers mean a lot in Scripture. Specific numbers, that is. Like uses of seventy, seven, five, two, etc... they all tie back in together.
When I hear "two or three" in that kind of statement, I think of the two or three eyewitnesses necessary to accuse someone of a crime--or, if I can
midrash a bit--to establish the truth of a situation.
I've been looking into the concept of the phrase "in my name" found so often in Scripture, especially connected with Jesus. The Hebraic concept of a "Name" is not limited to the letters and pronunciation of someone's given name. It's not so much a label.
Someone's Name is their
character, their person, what they stand for. So taking the Lord's name in vain, for instance... I don't think that means saying "Oh God". I think that means misrepresenting God's character and making Him out to be something He is not--in a sense, being a bad eye witness.
Here's a short explanation of it that I enjoyed reading. It at least made me think.
Anyway, so what about this "gathered in my name" business? perhaps us gathering "in the name of Jesus" means lifting up his
character and representing who he is here on this earth. Maybe it means when two or three of us are
witnesses --meaning acting as he would and being "Jesus with skin on"-- then the truth about him becomes known, and there he is with us because we're representing him in truth.
It's like making someone your signatory (not sure if that's the right word), or letting someone represent you in a situation where you cannot be present. You are basically letting them be there in your name and do what you would do in that situation So in a way, you are there because your ways and wishes are being carried out by your representative.
that's what i think this might be about.... not church, really... but representing Jesus to the world as a witness to make him known.