My grandfather had an excess of Balck Walnut and Honey Locust. It was painful to burn that stuff, particularly the black walnut that was so valuable. But like you, we weren't going to let it rot.
In MN, Black Walnut (in the form of green logs) being valuable is mostly an urban legend...or would that be a rural legend? LOL.
I've cut my share of Black walnut, and while searching out buyers, I always get some excuse why the logs I am offering are worth nothing. After those several failures, I avoid BW trees/logs. I won't cut it for firewood, I don't like the smell of the smoke, I suspect it has some level of toxicity.
Funny story, the last logs of BW I cut, was from a giant tree in a neighbors yard, wedged between two houses. The tree company that took it down, left the trunk logs in 10' lengths at the home owners request. He thought he was gonna get rich. After he was unable to sell them for more than the price of firewood, He asked me if I was willing to cut and split them (and all the other medium sized branches saved from the tree) for half the firewood as compensation. I told him I wasn't interested in ever burning BW because I disliked the smell and told him I thought it was mildly toxic. He then offered me money to cut and split all of it for him. He said he wanted it for campfire cooking and such, I told him that's the last wood I'd use for such, he didn't seem to care about my opinion. We came to a fair price of my labor, so I cut and split it all in one day. I was happy with the deal, until the next day, when I had some sort of allergy type symptoms, that I blame on breathing the BW dust. LAST TIME, I told myself, LAST TIME!