To clarify, the black walnuts were not planted in AB. Somewhere in the USA where they'd thrive. Perhaps you suspect not well for purely economic reasons though...
Purely economic reasons. Black walnuts are not a great orchard crop. They have thick husks and little meat in comparison to other nuts. If you want to earn money with a nut orchard, then great. Move to Georgia and plant pecans or to California and plant English walnuts. You'll be using improved varieties for the greatest yields and the best prices, so of course you'll be planting improved cultivars grafted onto specially selected rootstocks. To do otherwise is penny wise and pound foolish. Of course, using grafted varieties means you won't get attractive sawlogs from the trees when they are mature in 50 years. And yes, if you're a woodworker (like me) then I'm aware that people pay lots of money for grafted walnut lumber. Prices are high because of the difficulty of processing the lumber, and because there is only a small amount of usable wood in any given tree. The people who earn the high prices are the people who process the logs, not the orchard owners, and they
earn it. But let's assume that they just planted wild-type black walnut seedlings and earned a pittance from the nuts (it could be a decent amount, actually, with 5,000 trees, but most of the money would go to labor, not investment returns). We'll assume that the trees were pruned well as they grew to ensure top-quality sawlogs. After 40-50 years, the trees are finally ready to harvest, so now all they need is for 5,000 woodworkers to come pick out a tree, saw it down, load it up, haul it to a sawmill, pay the sawyer to mill it into lumber, dry it for 1-2 years, and of course, pay the orchard owners, $200 apiece for the privilege, and they're millionaires! Of course, they may convince a half dozen woodworkers to buy into such a scheme, but most of them just want lumber that's already been sawed and dried. So now the orchard owners have to cut the trees down themselves, and haul them to a sawmill, or better yet, buy a sawmill themselves! They can saw it and sell it themselves and pocket all the profit! But don't forget the huge barn that they now need to build to dry thousands of board feet of lumber. And they have to market and sell every bit of it.
Anyway. That was probably more detail than you want. Trust me, I've seen this story before. In fact, I mill and sell lumber myself on the side. So does my dad. But it is a real job, and real work. It's not a passive investment. Not even with $walnut$, which is the most overhyped lumber in the history of lumber.