No comparison.
If you buy(x) and it's defective or bad, you ask for your money back in return for the bad item.
You're not told to keep the bad item or else.
You're not told you have to BUY the bad item or the seller will retaliate by not selling you any other goods.
This is a better analogy, IMO.
I have a car for sale. You say you want to buy it. Initially I say ok, then change my mind and decide to keep it or sell it to someone who offered more.
Are you right to threaten me for not selling it to you? Tell me I can't drive through your neighborhood, or-perhaps not shop at your establishment?
Buying and selling should be voluntary. Reciprocation is good, but not mandatory. I don't have to buy clothes from you if you buy milk from me.
To threaten to keep me out of your store if I don't sell you my car is blackmail.
The stereotype of Arab traders is based on fact.
No.
A person has no right to keep somebody off the public streets in a neighborhood.
A sovereign country does have a right to keep our military ships out of their port.
I can threaten to never do business with you again, and tell as many people as possible to not do business with you either.