You are confusing two different types of transfer case designs. The transfer cases operated by a switch or button CANNOT be towed 4 down as they are in essence a clutch pack type design requiring internal pump pressure to operate.
The second type used by Toyota is a manually shifted two speed, high/low with neutral, design the same as found in many off road style vehicles. This design transfer case CAN BE towed 4 down in neutral.
One word of caution, Toyota does not certify ANY of it's vehicles to be towed 4 down behind a motorhome. That said the Toyota 4Runner TRD Edition with the manual shifted transfer case can be towed 4 down as long as you are willing to accept the loss of driveline coverage.
And before the X'purts start questioning the above, I spent 28 years with Toyota Motor Manufacturing, and retired as a senior vehicle design engineer.