If someone "just" bought something in your shop (as mentioned in the article) you shouldn't bother them. If you're running a business like this, managing expectations is a large part of your job.
When discussions with customers occur frequently maybe it's time to review how your business is communicating with customers. What can be done to prevent misunderstandings regarding using laptops/hogging tables? etc.
When discussions with customers occur frequently maybe it's time to review how your business is communicating with customers. What can be done to prevent misunderstandings regarding using laptops/hogging tables? etc.