Why the comma before "being" in the Congress Version

I think that there are overwhelming signs and evidences that the first comma in the congress version of the second amendment was intended to make stating "necessary to the security of a free state" from the authority of reality rather than that of making a constitution. Nevertheless while it may not be required, it would still be better if the benefit of the comma can be seen.

It seems to me that one of the big benefits of the first comma is that it directs thinking for evaluating the necessity of a militia (and that includes its sufficiency) to be on the basis of the existing environment  at the time  and applying generally on  any "well regulated" militia there rather than about a specific militia creation. That was emphasized more with the use of "being" instead of ,for example, "which is".

In other words the comma version shows that although the comma-less version makes the "necessary to the security of a free state" a requirement on the "well regulated" militia, satisfying or not satisfying that requirement actually dose not come from the militia itself and is not dependent on any specific structure or composition (other than being "well regulated") but is dependent on the  environment and  leads to one end result applying on any variation of a "well regulated" militia the same way.