Perhaps the question should be reversed ? Why does Horizon NOT want to order the DX7 from JR ?

Let's see... Horizon own Spektrum and therefore any and all profits made under the Spektrum brand go to them. Get the Spektrum factory to build 1000's of units and the cost per unit falls to a mere pittance, getting JR to make them means additional costs and of course JR need to make a profit and so the unit cost is higher.

The cynic in me also views this as a way to deny JR the DSMX firmware upgrade thereby locking them out of the consumers market.

Horizon have been very clever and probably have a greater market share than anyone else. As most people want the latest and greatest toys/version then the vast majority will want to upgrade to DSMX eventually. IF JR is locked out of this upgrade then current JR users will in time migrate over to Spektrum so as to prevent having to change out all their receivers.

Or am I being to cynical ?