Well he doesn't have a clue. Packers project to have 52M in space next off-season without releasing anyone. Certainly they won't have the room to wheel and deal like they did last off-season, but they can easily afford 7M for Jones if they like the value.
I would ask you to consider my post #264 in the "2020 Salary Cap Situation" thread. There I've laid out what the depth chart looks like for 2021 using the 30 players currently under for that year at a current cap cost of $163 mil.
What I did not mention is that there is not much in the way of potential big end-of-the-contract cap savings cuts in that list, a common source of cap space for teams with aging vets. Lowry at $3.3 mil is the leading candidate.
Thinking $52 mil is bounteous in that picture is highly questionable. As stated, there are two drafts in the interim to fill a lot of gaps but since it is not known which ones will emerge as player this season argues for waiting to see where the needs fall at this time next year.
That doesn't mean a Jones extension couldn't fit in that scenario. But if, for example, the Packers drafted high for an OT, with a consideration that he'd be a backstop against losing Bakhtiari in FA, and that guys turns out to be a Spriggs, then you might just want that Jones cap spend back in the pot.
In your fine list of "agruments against" extending Jones, the "Resources" paragraph contains only a glancing blow with regard to who might then become unaffordable in 2021.