This is my take on the plot.
Your theory might be somewhat true, you know why?
Because the teacher has a full map of this school, at the start of the game.
So he was there in the first place.
And there are no adults beside him...
But... lets analyze facts, because you also can be completely wrong. Look at the start of the story:
1)
"You have been aiming to become a teacher employed by the government.
One day you received a call.
Deep in the mountains is a school where you will be interning".
2) If the story is not lying, the main character was 100% certain, that he was called by the government.
He had a meeting with the government, was well instructed and got two maps from them. 1) to get into place and 2) map of the school.
3) He got into place and stuck there, with only kids and no adults.
4) The whole place makes the main character very horny (judging by visual display effects).
5) Kids are acting like imps, but with strange rules. Doing absolutely nothing at certain time.
Why like imps ?
5.1) they have aura of seduction, making main character less resistant.
5.2) the only thing they want, is a "white milk"
5.3) they can paralyze main character
5.4) powerful ones has demonic eyes
6)
Main character acts mostly careless and as he'd expect anything like that.
7) Space and time distorts after "death" and close to ending.
So the place make and impression of a warp to demonic domain. Something like that was in "The Witch's House", where at the beginning, the house was not the same that it was in the end.
For me it sounds like a mission, organized by government for SCP discovery.
VERDICT: So it seems, that he, wanting to become a teacher, was hired or just used (
because he thought, that he will be interning) by the secret organization, that is researching abnormalities and anomalies.
So, you could be right, if the main character was never met with the government and didn't got a map from them, getting to place just by phone instructions.
Or I am right, if the character was met with the government.
But if not, it's still possible, that
it was just a great prank from horny demons.
In any case, there is still a possibility, that anything of that is not true, and the story makes no sense at all, lol.