commodities-price inflation, or external inflation as I labelled it is not necessarily class war because it may be related to an actual scarcity of resources.

This is a well documented case for oil I think.

I really do believe that we should dissociate economics from politics here. Economics as in "study of the production mecanisms in society" are not political per se. mainstream media spin about austerity is political, because it serves the interests of a particular social group.
But the fact that economic lingo is used to promote an agenda do not imply that economical studies are not giving insight on which kind of societies do work, as in stable and productive societies.

Even in a context of huge de-growth to keep our pressure on environment and natural resources would we need economic studies.

Because the fundamentals of economics -when honestly done- is about designing a productive process that optimizes resources: natural and human (as in work and capital). You could have whole studies of economic parameters like money supply/inflation usw without having made the slightest hypothesis on inequalities or democracy.
But you can also, given an objective of democracy and low inequalities, look for economic parameters that would favor this kind of society.

Example: you might achieve equality with a strong state which directly manage all productive processes so that no capital owner would gain power from riches. Or you could give instructions to your central bank to permanently run a light inflation so that it would constantly erode the capital owned by the richer citizens.
The first method requires a numerous administration and may have some political and social drawbacks (corruption or a tendency to conservatism), the second is more open, as it leaves autonomy to the citizens to develop a professional activity that will have consequences in the economical field.
I repeat my assertion about the french society after the first world war and rentiers euthanasy at the time.