Seriously, that e-mail sounds like it was made by one of those Sinologists that want to conflate today's China with the China of the past to portray it as a global power in all of its historical periods and to compare it to European colonial powers, as well as containing the myth propagated mostly by Bernard Lewis that Muslims have an almost supernatural capacity to resist Christian encroachments on them more than any other people on Earth. No matter how ridiculous these claims are when they're actually scrutinised, they get repeated over and over by Western scholars and non-Western scholars influenced by the former.
The Sulu polity survived - as a small rump state - because of inter-European rivalry in the region, not because Muslims are anti-infidel fanatics in general and anti-Christian fanatics in particular that are almost impossible to subjugate. Had it not been mainly for the Dutch but also the Portuguse and the British, the Sulu would have been absorbed by the Spaniards much earlier than the 19th century, the same Spaniards who forced the Bornean kings Abdul Kahar and Saiful Rijal to flee when they invaded Borneo and practically annexed it to the Philippines for a couple of months. Anyone saying the Sulus are some kind of super Muslims who could defeat almost any Western colonialist that came in their way is doing nothing more than further propagate Orientalist mythology.
And it gets worse when these Sulu super Muslims get turned into instruments of the ultra-awesome global power of China (the same ultra-awesome global power that got conquered by a nation numbering less than 2 million people). They probably turned to assistance towards the Qing, but that doesn't mean that the Sulus were a "tributary" state, a term that has lost any meaning by being so overused by Sinologists obsessed with making pre-modern China an European colonial power. The fact that they have to use such an ill-defined term as "tributary" shows how weak their claims of China doing nothing more than just trade, like any other state and nation in Asia. I mean, by the Sinological definition of "tributary", the Mughal Empire was a "tributary state" to the Ayutthaya kingdom.
China was nothing like a colonial empire in any period of its history. The remarkable thing about China is getting its territory conquered repeatedly by foreigners (Xiongnu, Tibetans, Mongols, Manchu, British), not that it has always been a global ultra-superpower. Even today, China is more like a bigger South Korea than a proper superpower like the US, Russia and the EU.