There is a video of this small craft and after watching it I can see no obvious reason to park the ship and take a look.
If these guys had money for fuel to "go fish" then they had enough money for:
A distress Flag at the very minimum.
A small piece of Mirror.
A road flare.
Maybe even some Sea Dye.
They do not even seem to have OARS.
How tough would it have been to tie a shirt to an OAR
and use that as a distress Flag?

As others have stated there are a few reasons why a ship would not want to stop without actual proof of distress, Security is only one of them.
The Capt. at the time has assisted other vessels/crews.

Darwin sucks but does work.

It sounds like a cock-up rather than conspiracy to me. From the BBC report:

"Understandably, Capt Perrin is devastated that he is being accused of knowingly turning his back on people in distress. Had the captain received this information, he would have had the opportunity to respond."

Princess Cruises added that it understood its responsibility under the law of the sea to help any vessel in distress, and said its ships had been involved in more than 30 rescues over the past decade.

Skepticism is understandable, given that this cruise line has been in full damage control mode for months now.

That said, I find it unlikely that individuals in a position of responsibility and trust would deliberately ignore a vessel in distress.

But no question, it certainly is a cock-up, with serious implications. The only issue is how high it went, and who gets set adrift in a bedpan.

The account is not very detailed, but
many of the crew are probably low paid hotel staff, rather that professional sailors.

Inspite of the passenger speaking to an officer, it may actually have been a "hotel supervisor", and there may have been a language issue too ? Possibly the message never did reach a "real" ships officer ? From the sounds of it, they needed good binoculars to spot the fishing boat, and by the time they spoke to the "officer", they may have passed further away.

I'm not making excuses for anyone here !

The bridge should have had radar and they would have known about the boat.

Even if the Captain was unable or unwilling to stop himself, his duty should have directed him to notify maratime safety - especially if he suspected piracy (as some folk have suggested).

A prudent capatin could even have reported it as a "... I didn't see anything but a passenger saw ... " and then left it to maratime safety to do a fly past and check it out properly.

The absolute minimum would have been to enter it into the ships log !

Salient points, Aussie.

This raises an important sidebar issue: say I'm on a cruise, and I see someone I think is in distress.

Realistically, what actions and language do I use to ensure that the ship's command structure (rather than the dept. of concierge) receives the information? All this, preferrably, without being tossed in the brig as an obvious troublemaker and disturber of the peace?

If the crew is maintaining a proper watch on the bridge, your notification should e extremely redundant. Somehow one gets the notion that some cruise ships at least, are not up to snuff in some of the more basic aspects of maritime safety and good practice.

First thing, dial 911.
Report clearly what you have seen, where !
Then get the name/ID of the person you report
to, not just a "staff title" if your are able.
Getting their name/ID gives them incentive to promptly
report "your report" !

With all respect, I am not sure you have thought the matter through. Cell phone service does not extend to the open ocean. And bullying/intimidation often achieves the opposite of the desired behaviour.

The goal is to ensure that the message is credible, that it gets to someone with actual authority, and that action has been taken.

I think he meant the ship based phone network. The phones on a cruise ship are set to use "911" as the general emergency line so the landlubbers know what to do.

Thanks, matt_. I was not aware of that.