As someone in distribution and consumer packaged goods, this is 100% accurate.
The rub here is, who owns that other 50% stake. If it's Diageo, they can just torpedo the brand by not letting him go elsewhere. This would be painful on Diageo's behalf because they probably have a shyt-ton of inventory manufactured and contracts to manufacture more liquor that they will pay severe penalties on. But if you have someone calling you racist in the media, it might be worth it to take that L because it can damage the other 200 brands that they own.
If he can work with the other owner(s) and go elsewhere, the new distributor may not give him as favorable split on the profits. Owning is much different than distributing. This is why the "owning your masters" arguments in the early aughts was dumb. If you have no one to sell to, IT DOESN'T MATTER if you own 100% of something. Retailers don't just buy from anyone. There's quality control issues, there's issues if the company can't supply the demand. It turns into shelf space issues and lost sales that can hurt the retailer.
EDIT: As dumb as it sounds, I'm learning in my current role at work...an empty shelf is not as easy as "just put something else on it". You have to reset the whole display with new UPC. Believe it or not this takes WEEKS to do if you are a medium/large retailer like Wal-Mart/Target/Walgreens, etc. Think about all the times you went into a store, and shyt wasn't there and you thought to yourself, "they got more in the back". Half the time...no they don't, and no they just can't put something else there.
Every deal is different, and folks need to stop going to that "he's just an employee" rhetoric. Puff seemingly had a creampuff deal, but if he can prove Casamigos and other brands was sold in more retailers, than that is mad shady. It's kind of hard to prove however. Diageo is public, but it's hard to prove that Diageo deliberately subverted the brand or if retailers just didn't buy it as much...which I think is more likely the case.
The message to take from this who owns the other 50% and every deal is different. He definitely owns a large stake in the company, but he might be tied up in a dumbass contract, which is likely the case if he only invested $1,000.