The problem is in Amazon's storefront, and there millions of sellers are operating in the same space, so doing some due diligence is required. If Cliff could just seize ownership of his storefront from a thief, why couldn't a thief seize it from Cliff? The solution is to register a proper trademark.
Like it or not, the world is messy, and it costs to keep it clean. Registering a trademark is like buying locks for your home and vehicle, and buying soap to wash your clothes, and changing the oils in your machines.
This leaves small hobby stores like Cliff's with no practical defense against scams like this if they've only made a few thousand in profits through amazon sales, especially if they don't have that cash on hand (and suddenly lose their amazon revenue stream!)
Like it's easy to say "well you should have trademarked your product" after the fact, but very few people have even heard of this scam when it happens to them.
There really are no polite words to describe business practices.
Stop buying from Amazon. Quite easy actually.
There a software company running a software market, all the power is in there hands, and they choose to do nothing.
It's a little outrageous that a 3rd party can come take over your storefront without any avenue to challenge.