That seems like an idle threat. Hermes needs a "black market" to keep the brand in circulation. Making the item feel risky acquire can add to the thrill of the chase.

Maybe if you try to buy a truckload at once, they would step in, but I doubt any consumer-level flipping is hitting their radar.

Personally, I haven't heard of it happening. Most of the market is off resale websites anyways. Now if you started a boutique trying to resell Hermes bags, then you might have an issue.