My guess is the Furman administration or coaching staff didn't want to travel to Fargo. Furman actually has a history of pretty good OOC games compared to say, Wofford or Samford who plays a bunch of D2 schools. The SoCon has a history of playing a bunch of Big South or OVC teams OOC, which makes sense as they are economical bus trips but they generally don't help the SoCon SOS any.
The Mocs did play JMU in 2019 and were supposed to play them again in 2020 - that was a pretty good OOC game against a national top team. We also play JSU regularly and they are usually top 10, with the advantage to also being a short bus ride.
One thing that doesn't help is that the selection committee seems to reward wins more than SOS. Let's take a generic SoCon team and give them schedule A. - Wins 6 SoCon games, loses their money game to a P5 team, and beats two D1 Pioneer Teams OOC for a record of 8-3. They are in the playoffs for sure and the coach can tout that they are a playoff team and they have a top 15 ranking. Take that same SoCon team and give them schedule B. - Wins the same 6 SoCon games and loses to the same P5 team, but instead of two FCS cupcake wins, they have close losses to NDSU and KSU and a record of 6-5. That team is not in the playoffs and the coach is getting questioned why he can't get the team over the hump.
For the Mocs, I've always felt that for OOC games we needed one ranked opponent - that if we beat would be a quality win, and another FCS team that should be a win. That way if we loose to the ranked opponent, we still have a shot at the playoffs by going 6-2 in the SoCon and 1-2 in OOC play (let's face it barring a miracle, every FCS team starts out 0-1 with the money game on their schedule).