They'll lose to North Dakota and pickup their 5th loss. Won't make playoffs

I think you meant 2nd loss.

They have 4 losses now, including 2 to mediocre Central Arkansas in the fall.

My mistake. I haven't seen this before.

So they played a fall schedule that included Oklahoma and Central Arkansas (twice) (0-3), and now they're playing MVFC spring ball (4-1).

correct. Don’t know how the fall games are factored. I am guessing they are discounted to an extent or fully if the team plays a “full” spring schedule. I have watched their games. Their defense is very good. Offense has been sporadic but improving. Scott Struck (QB at Idaho state last year) has taken over at QB and is improving each week. I just don’t think 4 Missouri Valley teams should get into the playoffs, but there is still a bias towards that league. I think that South Dakota state will end up being the best team. Their loss against UND was an aberration- my guess is that SDSU, NDSU and UND will all be selected. The southland conference will be griping for multiple teams and will likely get at least 2 (Sam Houston and Nichols). My guess is that big sky will get 2 as Weber State has only Idaho State left as a test, and either the Ags or EWU will go depending on who wins this Saturday. EWU will not lose again to Idaho and we all know about cal polys woes. BTW- the highly touted Weber QB transfer from Middle tennessee did not look that good against NAU.

As far as your question on how the fall games are factored:

"Schools that opted to play games in the fall will have their results considered in the selection process for the spring championship field."

https://www.ncaa.com/news/football/article/2021-02-09/how-2020-21-fcs-football-season-will-work