And my point is, what they understood it to mean after 1776 is irrelevant. In the context of this discussion, only what it means in 1776s argues to the point.
Just that one year? The phrase "domestic insurrection" was used prior to 1776 and did not usually relate to slave revolts. And it was used after 1776, again, not usually in reference to slave revolts. And we're supposed to believe that in 1776 it was all about slavery? Not likely.