As a midpack D3 runner who ran at nationals in 2021 AND 2019, also at Louisville, I can confirm that the course was identical in length both years, and according to my GPS watch, a full 8k both years. I'm guessing you weren't there this year, so you have no grounds to claim it's short.
Granted, the course was covered in mud and standing water in 2019 and consequently did not run fast. This year, the course still wasn't in perfect condition. There were muddy spots - significant parts of the course were blocked off until the day before nationals. The officials did somewhat of a good job filling in especially muddy spots with woodchips and/or leaves. However, this was only for the literal mud pits on the course. More than 90% of the course is on grass (not hard-packed dirt, like the CA courses) and was soft. I used half-inch spikes for the race and I don't think it was overkill. The course was not in perfect condition this year, nor was it short. Times were ridiculously fast compared to historical D3 national meets, but that's likely due to supershoes and an overall increase in the competitiveness of D3.
As other posters have said, I have no reason to think that Newbury Park would finish higher than 3rd at the D3 national meet, and this is the most generous estimate. It is fair to compare NP's 4th to the top true freshman, Grahm Tuohy-Gaydos from Williams. He ran 8:57 last spring, NP's 4th ran 8:56. Let's say NP's 4th places 18th for the sake of argument, just ahead of Tuohy. That's a 24:07. Generous, but still somewhat reasonable.
Give NP's 1-3 some arbitrary places, how about 3, 5, and 12. Among the top 4, that's a score of 38. At CA state, NP's 5th was 27 seconds behind their 4th. Assume this gap stays exactly proportionate to race distance (which is overly generous) and NP's 5th is 43 seconds back at D3 nationals. This is a 24:50, and ~77 points. Which gives NP a total of 115, placing them third behind PP and MIT. This is the best case scenario anyone in the NP camp can hope for, otherwise they're just not willing to accept a logical explanation.
If NP had run D3 nationals, I think they would have been lucky to be in the top 5, and reasonably could have finished outside of the top 10. A 3rd place finish would be best case scenario for them. However, these are a bunch of 16 and 17 year-olds who have never run an 8k before. They're competing against a bunch of 20 year-old men who have been specifically training for this race and this distance for 6 months, if not much longer. Say one or two of the NP top five blows up - a plausible assumption given that this is their first 8k ever. There goes another 100 or 200 points to their score. Say they don't convert well up to 8k. Yeah, yeah, they run 8 x 1k. Well, they've never raced an actual 8k. Pacing a longer race is something you can only learn by experience. Let's look at their shorter distance times for a second. They're clearly geared towards 3k/5k rather than 5k/8k. Their top 4 might all run 8:30 this track season, according to Brosnan (lol), and yet they're only in the 14:25 - 14:45 range for 5k xc. Their 5ks are weaker than their 3200s, and if you extrapolate, they'd probably run 8k worse than 5k.
What else? D3 nationals would not be a time trial like the CA state meet was for them. Watch the race video from D3 nationals, especially the first 2 miles. It was PACKED. I can attest, I was in the middle of it. It was physical, there was pushing and shoving around every single turn, there were erratic speed changes. In the CA state meet, the NP guys could essentially run their own race. That wouldn't be the case for D3 nationals. They likely would have run slower than their Woodbury times indicate. Also, teams at this stage $hit the bed. Look at Wartburg - ranked 1st, finished 9th. If NP was actually in this race, I think they would probably all go out too fast, die, at least one of their top 5 would have an off day, and they could conceivably score like 400 points, putting them in the 12-18 range teamwise. NP lacks depth, and that really goes to hurt you in a championship race where you're not head-and-shoulders better than everyone else, which, in D3 xc, they're not.
NP is still the greatest HS team probably ever, not disputing that. But comparing them to D3 is apples to oranges. NP doesn't train for the 8k race distance or for the race conditions. Frankly, they've never had to deal with the adversity a meet like D3 nationals presents. Would NP win nationals if it were a 5k, or better yet, a track 3200? That's a different story. What is they had a whole season to train for 8k and race it a few times, and proved themselves decent at the distance? Also a different story. But that's not what happened, and that wasn't the original question. Hands down, NP wouldn't have won D3 nationals. Still a great team, and their top 5 clearly has the potential to have successful collegiate careers in any division they choose.