Instead of delaying the turn in and asking for an extension, he turned in the product he had to the company manager/interviewer guy with an explanation of why it was not completed.
Depends on the explanation.
If it's because "Well, I had daddy duty" or "the home needed major repairs" or "Hey, Cub's opener!

" then that's not a good explanation.
However, he got a second interview!

so his explanation was probably more along the lines of "I had some thoughts, but needed to do additional research in order to complete this task in the best possible manner."
So, yeah... does that still mean it is a good thing?
Yes. I think it's a good thing.
He can still ask questions, give the interviewers his thoughts . . . "I'm more than eager to learn. I thought about doing
this with the program, but I need additional input (answer my questions, he should have a strong list of questions) then I feel confident that I'll be able to come up with a solution.
The important thing is that he not bring any negative or self-doubt into the interview. "I didn't understand" or "That's beyond my capabilities." Even if he doesn't know the answer he should go in with his confidence and show the ability to learn and be a team player. (Yes. Sometimes you gotta "Suck Up."

)
I got a job once because there was a trick question on the test. They marked the question "wrong." I refuted the wrong marking because I knew my answer was correct. Out of 33 people, I was the only one that did that. I was the one that got the job.
Maybe? This is what the interviewees are looking for? Someone to take the initiative to question their test?
Or maybe not.
Good Luck, DH!

(3 responses while I was typing . . . guess I'm off track, but posting anyway)
eta: Art2002 put it much more succinctly than I did, but that's the point I was trying to get across. DH should show his desire to learn and his ability to be a team player.