Can't they just issue a redirect, either via dns or via nginx to github.com instead of showing the page if it was truly altruistic?

That could pose its own ethical issues, especially if companies start accidentally creating documentation and links to guthib.com without realizing it's redirecting them. At least this way it's clear you've made a mistake.

I doubt it was created to benefit others, it looks more like a joke to me.

My point was, I believe the person who did this is is partly - aside from the joke aspect - trying to get it at the top of HN which will cause it to have a fairly large amount of traffic, which will in turn potentially lift the price point if they offer to sell to GitHub. After all, if you can show ppl commonly make this mistake when trying to access GH (hence the large amount of traffic), it incentivizes them to buy it. That is also why there is no redirect, because that would eliminate GH's need to buy it to begin with , since the end goal is already taken care of.

And even if this is not what they intended, they should now. I believe it's actually quite a clever way to add some value to this domain.

As pointed out by another comment it looks like this is a joke from GitHub itself, as they own this domain.

I think you are referring to my comment that said guthub.com is owned by Github, not guthib.com :)

Ah of course, I didn't notice it was the same person.