I don´t think it has to do with how many pieces the ammunition comprises of but from the overall design needs of the tank.
??
The ammunition configuration (aka the requirements of the primary weapon/main gun) is of course one of the design features of the tank.
When we talk about the ammunition configuration in relation to the type of autoloader the tank has, it is all in context of the overall requirements and design of the tank...
The tank needs to be as light as possible without sacrificing tactical qualities. Hence the adoption of 2 man crew. That leads to the tank being made narrower which is where much of the weight saving comes. But the tank being narrower also places further limitations on what can fit in the hull, like for example a carrousel autoloader. The size and amount of the ammunition to be placed on a carrousel depend on the volume that is available for it. Thats why T-14 has such as huge internal volume dedicated to the autoloader, can fit very big ammunition (ready for 152mm that can be more than a meter long) and in very large amounts (31 rounds of 125mm). ZTZ-201 comes from a different doctrine, hence it makes more sense to move the ammunition to a bustle autoloader. Once the ammunition has been moved there the next choice is the specific caliber. In this respect 105mm presents several advantages over 125mm: the gun will be lighter, the bustle can house more rounds and the ammunition format is already in widescale service and mass production.
At this stage I wouldn't be confident to say the tank has only two crew.
There are two hatches yes, but it appears like there may be three periscope positions.
As for the rest of what you've written, I do agree with you in theory but having single piece 105mm ammo does also mean that certain types of carousel autoloaders in the hull are not practical due to the length of the ammo itself. Of course there are also other reasons that would make a bustle autoloader more sensible (and vice versa).