Hi,
I think the problem is in that, when thinking about a possible Chinese colonialism, we always have as the standard European colonialism. So if the Chinese "do" colonialism, it has to be a variation of the European phenomenon, otherwise it isn't "really" colonialism. So we imagine the Chinese literally conquering and installing viceroys, massive emigration of Chinese to the colonies where they subject the natives to third-class status and implant an extractive economy, etc. That would be "normal". But I think it is the other way around. European-style colonialism, the one that emerged since the late XV century, is a very unique phenomenon.
What made European-style colonialism even possible was that they stumbled into a region of the world with a massive power imbalance with respect to them: the Americas. A whole continent(s) full of resources and people who died literally on contact, and those who survived only with a stone-age military technology (whatever other advances they had) to oppose you. And to cap it off, full of what you desired the most: gold, silver, new crops, etc. And to cap off the caping off (hehe) sitting at the end of a clear sea route facilitated by prevailing winds and currents, making it within reasonable reach of your naval technology. The result? Europeans could impose their will, their cultures, their very genes in a way that nobody else could to any other people. So they colonized all of the Americas at will, while fighting each other nonstop.
The Chinese case was nothing like that. No population that biologically and culturally vulnerable was within reach (forget about Australia!), that had even remotely a similar payoff as the Americas. So they could politically dominate neighboring states (and they did), and export a merchant class (just about everywhere in Asia, as they did) but never pull out an European-style colonization. External conflict wouldn't had stopped them, the same as in the European case.
Or, to say it another way, if the Chinese were in Europe and the Europeans in China, it would have been the Chinese the ones to overwhelm the Americas and thus define "classical" colonization.
Geography, gentlemen. Geography.
Chinese-style colonialism is closer to the historical norm. It is European colonialism that is off the charts, due to the vagaries of geography.