As someone else noted, Amazon sent a cease and desist letter when someone tried more-or-less the same thing on them (https://www.aboutamazon.com/news/company-news/amazon-perplex...), so it's absolutely a double standard, yes.
But that doesn't answer the question of what rights vendors actually have here (much less what rights they should have).
copyright on pictures, text descriptions, use of their brand names?
The fact that Amazon even allows vendors to request de-listing (and the fact that Amazon does it promptly) would suggest that Amazon's lawyers have recommended that they do this (and that it's likely for a good reason).
We, as non-lawyers, may never know. But they obviously know something... Enough to spook them.