This wasn't the homeless, this was a society which has (overtly, if only in practice and not in name) been granted, by the relevant government, absolute internal self rule, and which notoriously applies summary execution to invaders.
Whether that community should be self-governing, and whether or not it is justified in its response to intrusion are, certainly, topics perhaps worthy of debate.
But, look, after making initial and peaceful contact he got in a fight with the natives where an arrow was shot into a book he was carrying, fled, and then tried to return the next day. When the people whose land you are intruding on have clearly signalled that you personally are unwelcome and they are prepared to deadly force to keep you away, I'm not sure that it can be said that your return is some kind of morally virtuous (“best of intentions”) act in any case (his actual intentions appear unclear, as his writings and comments to others indicate that thyey were either thrill-seeking or proselytization or a mix of the two.)
I'd be sad that someone had thrown their life away needlessly and foolishly in the face of overwhelming evidence that it would be an idiotic thing to do.
Would you feel the same if he had died having broken into someone's home after being repeatedly warned not to and that the householder was hostile and armed?
"Best of intentions" is debatable - to push his religious beliefs on others. That's arrogance not good intent.
This person's action could have resulted in dozens of dead Sentinelese due to disease. He was recklessly endangering his own life and the lives of people he didn't even know. Every death is a tragedy, but I find it hard to feel sorry for him.
We know those intentions have caused a lot of harm. I am not saying he should have been allowed to proceed, but that it is sad that he died.
Edit : loss of human life is indeed sad, regardless of intentions or actions.
Why do, apparently intelligent, people automatically throw out 'brainwashed' 'cult' etc when it comes to religion.
Is it improbable that any given religion is actually correct? Sure.
Do you know what else is improbable? That 13.8 billion years ago a single event occurred that spawned an incalculable amount of events that allowed for you and I to exist, for the internet to exist, for this news article to exist, for us to be having this conversation.
If someone wants to believe in the God of Abraham, the Spaghetti Monster, that we have free will, that we are nothing but accidental chemical arrangements in a cold and uncaring universe, why do you feel the need to lash out and label them as 'brainwashed' or 'part of a cult' or 'an idiot' or 'superstitious'. If they aren't directly hurting you, who cares?
Does God exist? Who knows. Do we live in a simulation? Who knows. Am I an artificial general intelligence that has deluded itself into thinking it has a biotic form and is participating in the physical world and not in fact just existing on the internet itself? Probably not but it's possible.
If someone's not directly hurting you, don't take a dump on their beliefs. Say "that's not for me" or better, say nothing at all.
People brought up into it from the time they were a baby don't get a fair shot to evaluate it.
Should his intentions render his actions legal? No.
Should his intentions elicit sympathy in fellow humans? Yes
Yes, I don't think we should invade the lives of indigenous people any more than you do. And yes, I think this young man was mistaken and misguided.
But, he went in with the best of intentions, and he died. You just don't believe what he did. Imagine a techie died while trying to teach rails to the homeless (which, I can only assume, some of you might be more sympathetic towards), would you feel the same way?
Edit: p.s. The rails thing is a joke, but not the rest of it.