True, but I wouldn't get your hopes up yet.

M is a middle of the road economy fare and tends to have pretty wide permissions for rebooking and minimal cost, since many of the fares are similar.

I subfare ex China biz tickets are literally the cheapest biz tickets in the network these days I think, and they are highly customized for each point of origin IIRC. For example in China ex-Beijing and ex-Shanghai are separate rates for I class. And there are also a lot of fees slapped on for things like stopovers, changes and whatnot. They seem like they can be an amazing deals but you really have to have some time on your hand or mega flexibility, and then not need to change. I've looked into taking advantage (my company seems like a perfect candidate, we fly to China frequently on top of our intl travel) but we just cannot make them work like I read on here (guys quoting 20k RMB for tickets etc.). All this means I think your odds of the ex-CTU I fare being the same price isn't as high as the other fellow's M fare swap.

Let us know how it goes and good luck.