If Slack employees said they felt is was unethical to serve chocolate over vanilla ice cream, none of us would pay attention.
Maybe there are situations where it's justifiable to sell goods or services to a PD (if there are situations where it's justifiable to buy a smartphone or laptop, this is probably the case in my opinion) but it's still unproductive to dismiss someone who disagrees out of hand. They are probably disagreeing because they have a strong moral feeling about the practice, and it's worth respectfully listening to the reasons they have for feeling so strongly, rather than dismissing it out of hand because you don't think it's feasible to implement universally.
My original comment was the opposite of an out-of-hand dismissal. I thought about what he was proposing, carried it to it's logical conclusion, and showed that it was flawed. I then invited him to propose a fix. No fix has been suggested.
> I think it's more appropriate to carefully listen to the compassionate concerns of others than to try and develop ways to ignore them.
Strong, unprincipled moral feelings come to every human since they are a small child. There is good evidence that these are very biased and lead to results that are immoral upon reflection. The world is awash in people announcing their unreflected moral feelings, and these point in contradictory directions. "Listen to this particular random person's feelings....but don't challenge their validity" is not useful advice.
[0]: On the grounds that when you give someone something in exchange for a promise of theirs that you are using them as a means to an end. [1]: https://www.washingtonpost.com/archive/opinions/1999/09/11/a...
Belittling another person is the last thing I want to do, so I'll thank you for the opportunity to improve my manners and drop the issue here, sincerely wishing you the best.