They didn’t mention it, because they want most buyers to use their subscription service and only purchase digital games, which have larger margins, no second-hand market, don’t drop in price as quickly and as often, can be delisted and removed, etc.
It’s also great without mods. During my first playthrough, a tornado destroyed most of the village, including the school with every child in it. Up until that point, nobody had died. All livestock, all crops, every single house was gone. The only thing that saved the survivors just before the next winter was some fruit I had stored in the dock for future trade. I managed to get them through the following winter and they all lived to die from old age, but the village never recovered from losing the entire next generation. I was only able to stabilize the population; growth ended up being impossible after this disaster.
I love games that are able to organically create stories like this one.
Sometimes, when I play a AAA game and something expensive is visible on screen (e.g. half of New York getting destroyed during that long quick-time event in Spider-Man), I like to shout “Production value!” at nobody, like that director self-insert kid in “Super 8” (2011).
I get a feeling I would ruin my voice doing this every time in GTA 6.
To answer your question, I think we would have to look at what music licenses usually cost. Some quick googling tells me that $7500 is hardly an outrageously low sum for a song from a middle of the road '80s band. They aren’t exactly Depeche Mode. I think they would have benefited far more from the inclusion of their song in this game financially (since it would cast them into the limelight again, providing streaming revenue and perhaps gain them new fans) than the little and likely very temporary publicity they gained from rejecting the offer.
On one hand, this does sound plausible, but on the other hand, Concord is such a disaster that said C-Suit idiots might legitimately fear that the mere existence of its episode could overshadow the entire rest of the show. It might be cheaper and more sensible to just write one episode off and, if there is any hint of an overarching narrative, fix this with a few edits to other episodes and maybe some quickly recorded voice over to bridge any possible gaps.