You know, sometimes people just start having fun. Especially after playing in the same game for three or four years.
Personally, I got "piano'd" three times in a row because of the "Psychopath" ability. And that was all from the same person. There was even a case where I didn't vote for him, but he still targeted me. The rules allowed him to target anyone if they were executed.
So, anything can happen.
Moreover, not so long ago, I encountered a mountain archer in a game who thought he absolutely had to shoot every night and eliminated two strong mountain roles. But that's not the point.
Right now, there are objective reasons why the mountain archer might not shoot:
1) There's no discussion on day zero => it's impossible to choose a candidate.
2) Evidence will be given for the shot => there's a high chance of revealing yourself to the mafia too early.
After that, there are subjective nuances, depending on the quorum.
BUT
You're not from this forum, so at least the main part of the quorum is unfamiliar to you. But why are you so confidently stating that a shot should have been made?
Why? Do you want to provoke the mountain archer?

Барон "Vampires"
Отдай свои прошлые сны,
В сомненьях себя обрети,
В бешеном танце душа кружится!
Не думай, что будет потом,
Здесь и сейчас мы живем,
Стань хоть на миг сам собой, слышишь!