If there is a shop willing to take the risk, I am willing to take the risk as well and support them. But we need a vendor to be willing to take the risk. Then the problem is, the rest of them need to be willing to either let those vendors take the risk and serve the community while they don't make any money, or the need to get onboard themselves. You'll probably find that one vendor might not be willing to take the chance and don't want others to make money while they lose out, so they'll end up reporting the vendors that do trade.
You're going to run into this issue... It's not up to the vendors.
They can sell what they have in stock. But when they run out most of them store their products in labs which won't bottle or distribute the nicotine for them. Their suppliers won't replenish stock either.
So sure, many might move the nicotine they've got on hand. But ultimately it will run out and it won't be able to be replenished.