From the sound of it this guy has the same problem with us that Lucan, Lucian? Whatever the hell his name was, had.
They don't like that we're more than willing to boil down practically everything (and to a lesser extent everyone) into numbers and treat every situation we have into something that can be mined for some kind of resource or opportunity.
That being said I don't really see how else we can act because from the looks of things about 85% of the local universe very much wants us dead or worse.
We're essentially in a War economy, it's just that the war is so large, spread so wide, and will take so long that such a situation is our baseline. From outside of course this would seem insidious, at least to those who can't get a seat at the proverbial big boy's table. We're grabbing territory left and right, seducing kings and queens into, if not fealty, then at least favorable trading terms, and growing at an exponential rate due to the fact we're the only game in town with a magical industry. (or we were until the fucking sultan- no no, we'll deal with him in time...)
For the people actually sitting there though they can see full well what's at stake and barring those few who are looking out to keep or raise their standing in society, mostly everyone is on board with the "get as much weaponry, resources, walls, and trained professionals between us and the ever growing cancerous mass of apocalyptic ends barreling towards planetos at full speed." operation we've got going on.
I say let the grumble, within reason, so they have an outlet for their frustrations and we can all get on with things. People not being satisfied with the status quo has been a thing for as long as there's been three monkeys in a group. Not really much we can do about that barring telling them just how far things have fallen and then their minds will break and they'll start worshipping the things trying to eat them and it'll just be a whole mess of tentacles again. (why is it always tentacles or bug parts. Why not a kitten apocalypse for once?)
It is worth keeping in mind that has far as you know this particular bard, this particular storyteller is not some mastermind, he is just a guy retelling a traditional story in a way that serves a political agenda that is opposed to yours. This is not a matter of 'this character who is a PC is being antagonistic'. Rather the consequence of failing a diplo action and then not taking a followup is that sentiment against the Imperium and its ways and practices is starting to crystalize. For the moment it is hard to tell where though there is certainly a religious element to it. Just thought I would get that out there so you guys do not focus on the person over what he is saying and miss-aim your efforts in this regard