I do not want my credit card to offer moral guidance, I want it to buy stuff were it is convenient. Where will it end, my bank telling me I have bought too much alcohol this month?
Your regulators (assuming you bank in the US) disagree with you. Banks have denied service to all manner of people doing relatively innocuous stuff. If the moral compass turns against gun purchasing and ownership sufficiently, there is a banking regulatory model in place to deny credit card processing to armament vendors.
Appeal to legality. A similar argument could be made that this would be to stop mass shootings, meaning this bank ban on guns would fall under legal grounds, not moral grounds.
I'm not entirely sure they should be liable. A car manufacturer isn't liable if someone commits vehicular homicide, and McDonald's isn't liable if someone eats themselves to death with Big Macs.
Devil's advocate: are you really paying them for a service? I guess it depends on if you pay your bill in full each month, but for those that do pay in full, credit cards provide so many "free" benefits (travel perks, cash back, loss protection, extended warranties, so on). So for those, credit cards provide excellent services requiring no payment at all--it could almost be seen as a club with benefits that one joins, and if that's the case why not impose their moral compass onto its members (like most clubs do)?
None of those things are free to me. It's something in the range of %1-%3 of all I spend. Despite the fact that a lot of the time those charges are hidden in the price of the items I purchase, I pay them even if I use cash.
As the article outlines, they already do by not allowing you to purchase cryptocurrencies.
I don't see any logical reason why "I'm paying them for a service" means they can't impose restrictions on the service they offer, except in the case of a monopoly, in which case there may have to be regulations on this.
The cryptocurrency decision was driven by higher than normal share of chargebacks. Even if the consumer is wrong, and bank eventually denies a refund on that BTC @ $16,000 purchase, there are processing and overhead costs that impact bank margins.
