You are right this is not a monopoly. However, it is also unenforceable.
If I have a brick and mortar store which receives product from GW, what is there to stop me from setting up an online store that sells them on the internet? Nothing.
How is GW going to know how my e-business store gets its supplies. The answer is they don't. So they can't stop distributing to my brick and mortar store that supplies my internet store.
In the end it is the consumer and the brick and mortar guys who suffer.
The brick and mortar guys already have to buy in ridiculous patterns just to satisfy GW. GW can already do whatever it wants with its brick and mortar stores and get a huge profit since they sell retail only.
Several years ago GW promised FLGS that it would not put any of their stores near the FLGS. Then they went ahead and put several in a highly marketable area right in the neighborhood of those FLGS's. So the idea that GW is looking out for the interest of the little guy is simply ridiculous.