Being a Christian Taliban, the "tourist" was asking for it:
A police source told Reuters that Chau is a preacher who had visited the area in the past and had a strong desire to meet the tribe. The source also claimed Chau expressed interest in preaching to them.
Furthermore, Andaman and Nicobar islands are off-limits to most tourists by Indian law I believe. The dude wanted to "save" the souls of infidels living on the islands and got what he deserved.
I guess he wanted to be the first to convert the tribals! What a fool-in this day and age!
People never learn. Picture below is of St. Adalbert - Prussians politely asked this preacher to leave, but instead he started chopping off some trees. Result shown below. At least he became St. Adalbert, and there are two sets of his bones incl 2 skulls - one in Prague, other in Gniezno.
As to the wanting to proselytize the natives, I think this guy missed the first rule of being a good missionary. Know your audience. These don't seem like the kind of people you just walk up to.
Very effective