I believe this is all part of a wider picture. With no electric double decks on the horizon, due to there being nothing that suits the needs of the company, something is needed to replace the aging Omnidekkas which for whatever reason they don't want in the fleet. Therefore the Navy 4 needs replacement buses, of which there is nothing avaliable in the fleet. The Navy 48 is the only double-deck contender to become single decker, and therefore it's buses will transfer to the Navy 4 allowing the Ommidekkas to be withdrawn.
I believe it's worth the cost of the one extra bus and going single deck using subsided Yutongs, than it would be to buy a whole new fleet for Navy 4