Is this the defense of your choice to support the industry? I'm not sure I understand it, as the same logic was/is used to justify slave labour and systemic racism - "they want to work, the children enjoy helping their parents in the field". Doesn't this ring sour to you?
It does indeed, but there is a salient difference: I have no influence over the economic policies of the countries from which cruise ships draw their labor forces. If I did, you would be absolutely correct that I would not have any claim to the moral high ground. But I don't, so AFAICT giving them money is the best I can do under the circumstances. If you have a better idea, I'm all ears.
I would also point out that this kind of "exploitation" seems empirically to be effective at lifting large numbers of people out of poverty. It's far from ideal, but it nonetheless produces better outcomes than anything else that has been tried.