When our relationship with our employer starts to seriously disrupt those that have bought a ticket to fly with us, then I'm afraid it does become their business and they have every right to ask questions.
If people have a problem with the product they have purchased they should take it up with the company via the relevant department. Their business is with the company not individuals or groups of employees.
The terms and conditions of employment is a matter between employer and employee only, it is nobody else's business. If anybody believe that the relationship between employer and employees affect the product offered, then either don't buy the product or address any grievances to the company. It is not ok to personalize it by singling out individuals or groups.
As I said, luckily it seems to be only the same handful of people who believes that purchasing a product from a company gives them certain rights and entitlements that extend beyond the product purchased, including the personal affairs of employees.
That is just not on.