The BB took less for Jimmy G story was always dubious at best, and mostly paired with the "Bill wanted to trade Tom and Kraft forced him to trade JG" conspiracy, it's pure conspiracy that flies counter to every move BB has made in the past."Screwing your direct competitor" is not always at the expense of your own best interest. If you can get a "pretty good deal" from a non-competitor, or a better deal from a direct competitor but that makes their team better, there is logic in "screwing the other team". Not always, but sometimes.
And there are definitely emotions, with GM's and owners. Maybe not as much as we sometimes think, but emotions are always 9or at least often) at play.
Isn't there talk that BB took a little less when he traded away JG, because he wanted JG to end up somewhere with potential? What drives the difference between "dumb emotional decision" and "intangible decision that isn't all about the short term zero-sum balance"?
Good GMs don't care, nor should they, there are basically no such thing as "direct competitors" in the NFL, intra division trades happen all the time because smart GMs know that you take every single ounce of value you can get. Divisions don't matter in the WC era, what does matter is the marginal value to your team you left on the table, which now means you lost an intra-conference playoff game because you were worried about someone else's team instead of your own.