It could be many things and anything is possible, but just should mention for example that Horizon has discontinued the 90 size ShowTime which is a much loved plane. To me that's an indication that sales are hurting and they are being forced to downsize. So even if the plane is popular, they are having to stick with the smaller size ShowTimes which might be marginally more profitable.

They might not be in dire straights but consumers are adjusting their spending habits.

Could be just an executive decision. Also I think that most if not all of the developers have entirely different day jobs. I recall that Selig is prof of aeronautical engineering or something and has been involved in all sorts of projects. So that can complicate things. Who knows.