An idiot who seriously endangered everyone who would have been involved in his, let's say, initiative and paid an obvious price for doing so, but I remember being disturbed by some of the transparently bloodthirsty glee I saw among various "decolonial" personalities on social media at the time that his death was first reported.
On the other hand, I don't know if it's really that different from people on this place cheerleading for the Ukrainian army.
If Chau had succeeded in his aims the likely effect would be the mass death of the Sentinelese due to disease and general exploitation--as has occured for other native Andamanese groups, a fact which almost certainly is a major motivator for the Sentinelese's hostility to outsiders.
Chau's intentions are a lot more sympathetic than Putin of course, probably moreso to you than to me, but the likely results of his actions would be pretty obvious, and he'd have to be pretty dumb or cruel to ignore that. There are a lot of people who you can convert to Christianity without killing them!