Couple ideas:
1) You could create a new location and set the specific products to be inventory managed by the new location. Then instruct your fulfillment team / partner to not fulfill items from that location.
2) Or if you want the whole order to be ignored, you could tag these orders, and instruct team / fulfillment to ignore those orders. If you don't want to manually tag the orders, you can use Order Automator to automatically tag orders that contain certain products. You could even attach a notification to the tag, sending a notification to the wholesale customer's team when these orders come in.
