But the usage of "Liberty" only makes sense as the liberty of self-governance through the Assembly. As I read that paragraph, Franklin is rebutting the hypothetical counter argument that the governor is simply doing what he must to keep the frontiersmen safe in exigent circumstances. (I.e. s/frontiersmen/children/--Franklin is anticipating the "but think of the children" deflection.) And Franklin is saying 1) at that very moment those who want arms have been armed, 2) all the Bills the Assembly has tried to have signed by the governor have been precisely to help for their defense, and 3) that any frontiersman willing to give up the "Liberty" (i.e. his right to implement policy, and particularly defense policy, through the Assembly) for whatever additional modicum of security the governor's plan might temporarily provide deserves neither the liberty being denied him (vicariously via the Assembly) nor any security.
Even ignoring all the other paragraphs, in no way could the liberty imply the frontiersmen's individual freedom (or civil rights, as we would call them). The contended Bill doesn't encroach on the frontiersmen livelihood or freedoms; it's a Bill to raise money for their defense (it literally says that in the next sentence) by taxing proprietary estate holders, who are definitely not the same people as the frontiersmen. It doesn't effect the frontiersmen directly, except by providing for more consistent defense funding. It's a pretty difficult piece to work through and I wouldn't claim that I fully understand all that Franklin is arguing, but whatever he is saying there, it can't possibly be referring to individual freedom. There's not the slightest hint of such a connotation. Rather, whatever the precise point, it's clearly an equivocation of the Assembly's rights with those of the People.
Yeah, he uses that phrase again years later and the arguments are different in those contexts, but it's obviously a cool phrase. Of course he would repurpose it to suit whatever point he's trying to make.
For others' convenience, here's the whole thing: https://founders.archives.gov/documents/Franklin/01-06-02-01...