Something to consider- We do not know the text of this Treaty. There may very well be sections of it that are construed as an "Agreement". An agreement does not have to be approved or ratified. It would not have any bearing on our Constitution but it may very well define things such as importation of foreign made arms and components.
Imagine no firearms/components of foreign manufacture being imported.
No foreign made ammunition.
No parts kits.

Even if not ratified it can still have very serious and deep implications to the American firearms community.