See, to me, these two statements illustrate the main problem with alignment and are contradictory.
There's nothing at all contradictory about those two statements. At all. In fact, they are complimentary with each other.
First, why would PCs decide to kill or capture and interrogate some hunters? There are in-game reasons, yes: perhaps the hunters wear the livery of the king and the PCs are trying to get info on the king, whom they know or believe to be the bad guy. But--and this is, I feel, more likely--they could be capturing the hunters because they're orcs. And everyone knows orcs are evil, because every MM has said so. If I had written "elf hunters" or "human hunters" instead of orcs, would you have written this reply to me? Somehow I don't think your first thought upon seeing a group human hunters would be to kill them or capture or interrogate them.
There are literally thousands of reasons. The hunters might be close to a human town and they might want to know where the hunters are from. They may want to know how many other hunters and warriors are in the area, because they have to travel through and want to be prepared. Or... Or... I mean, the sky is the limit with why they might do it.
What I've never seen, is capturing orcs because they are orcs. I've seen plenty of kill the orcs because they are orcs, but never a capture. I mean, what's the point?
And this is the major danger of having alignment: it encourages lazy gameplay. There's no thought involved in either planning the encounter or playing in it, because you can just throw orcs at the PCs--even orcs doing incredibly mundane tasks like game hunting--and the first thoughts are to interrogate and/or kill them. Not negotiate with, not help out, not trade with, not follow and see if they're up to no good, not avoid. Just violence.
It's not a danger. It's not even a worry. I've never seen it and I've played in a myriad of groups from RP heavy to power gamer to a mix, to sand box, to railroad. And really, you need to stop calling how we use alignment "lazy." It's quite frankly insulting and unnecessary.
As for helping, following, etc., that really depends on how orcs are run in the game. Are they generally a great enemy of all, or are they just another race with good and bad, if a more bad than other races.
But as to the contradictory statements...
There were none, but let's see what you say.
Imagine the PCs capture and interrogate the orc for legitimate, non-evil-listing reasons. You have the description "becomes hostile if the PCs scare away prey." So if the PCs capture the orcs and say "why did you attack us?" You have your answer right there: "You stupid humans with your clanking metal armor came into our woods and scared the deer away! Now what am I supposed to feed my kids?" The orcs aren't going to become hostile if the PCs don't interfere with them. And you--who presumably improv lots of different actions for your games--can decide what happens if the PCs choose to help the hunters instead.
Okay. But only screaming in anger and being hostile is just a one dimensional cartoon character, and I don't run those. Maybe he gives that answer and the PCs don't accept it and continue interrogation. Maybe they include threats. Maybe they promise freedom. Maybe a hundred other things. I need to know FAR more than just "hostile if interrupted" in order to play the orc and alignment is an invaluable tool for that.
But if you have the description "chaotic evil" then what's your answer? "You stupid humans came here and I'm evil so I attacked"? Or "Expletive deleted you, you stupid humans!"? Seriously. People keep saying that having the alignment helps guide them, but when I ask them how, they don't answer.
Nope. It helps me know how he might react to various things. If threatened, he's likely to cow to the much stronger force that has him captured. With CE might makes right. The weak bend to the strong. If they offer freedom, he might take the now weak in his eyes PCs(who lets an enemy go!?) up on their offer, then get a few dozen buddies and hunt the group down to make the PCs his captives and show THEM how a captor acts. Alignment tells me a lot.
But here's why it's contradictory: before, you write "It tells me which box they mostly play in. From that I can pick actions which reflect that box." But what I wrote also gives you a box--and it's a much bigger box. Why is it easier for you to pick actions out of a box marked "chaotic evil" than it is to pick actions out of a box marked "game hunters who will become hostile if their hunt is interfered with"?
Your box is useless for what I needed above. It's also far smaller than alignment ever could be.