People transported loads of camping necessities to a little island from a boat through waist-deep water. The job just finished only seconds ago. You are a college student on vacation, fresh out of grueling finals, lying sprawled on the seats at the front of the boat, being lazy.
You :I'm on vacation. I feel no need to volunteer my services. Everyone should be a slacker now and then. As Confucius once said, 'He who does nothing is the one who does nothing. Your friend: Did Confucius really say that? You: No, but who cares? The point is, they had it handled, and most likely they found some sort of self-satisfaction in their industriousness. Who am I to deprive them of that?
It may be just my construal, or misconstrual, of the 'have + something + past participle' in that particular instance that's hindering my full grasp of the phrase there, but somehow had it handled sounds like the distant past. I think you would naturally like to mention how they most likely feel 'now.' Normally in AmE the simple past can oftentimes substitute for the present perfect, which refers to time up to the present. But this only applies to action verbs, or so I think, and 'have' is often used to impart a sense of state.
I wonder if this construct with 'had' could deliver a sense of achievement the effect of which continues up to the present?