This guy is looking at the long view. If you read it to the end, he's starting his own garlic farm and is going to constantly undercut Jim's prices, so that Jim won't make any (or many) sales, until Jim goes out of business. He's doing this even if it means a loss for himself; his goal is to ruin Jim's business.

Now, this is what's known in Birdman culture as "a Dick Move," but Jim seems a bit of a dick himself. However, while it might screw up the beginning of my season, if I were Jim I'd simply pivot to onions.

It all comes down to how far OP's poster is willing to take it. He certainly seems petty enough to pursue all paths, at whatever cost, to prevent Jim from being able to still produce at that farmer's market; changing crops as Jim changes crops. If Jim's invested enough, he could rotate his crops between a half-dozen different root stocks and the odds Vengeance Boy would happen to match whatever he's selling that season would be slim and spoil his plan.