That person often has contradictory wishes. In this case, for example, it's likely that the person paying them to do the work wished for ^F to move to the next message and for them to build the best product for their customers.

Good management involves prioritizing these things in order to sort out the contradictions, and good employees help with this process by pushing back against directives that contradict what appear to be more important goals.

I'm thankful that we're (very) slowly moving away from that idea. That's what they pay Product Owners for.

Good PO/PM's care about the integrity of the product enough to argue with a CEO, but developers intrinsically have extra motivation beyond just "product integrity is valued!": every additional iota of product crappiness is painful, every time they touch it.

It would professional to strongly argue if their opinion is not for the best of the company. By strongly, I would see an argument like "You're the boss, but what you're saying doesn't make any sense because X and Y and Z."

In this case, isn't that ultimately the customer, who's now here wondering why Ctrl+F doesn't map to find?

That's irrelevant. The customer pays business (the owner). If the owner does something against his customer's interests, then the customer has the right to shop elsewhere.