In vinaya there are two occations where the group of six monks have committed a pārājikā offence.
Tena kho pana samayena chabbaggiyā bhikkhū rajakattharaṇaṃ gantvā rajakabhaṇḍikaṃ avahariṃsu. Tesaṃ kukkuccaṃ ahosi—“bhagavatā sikkhāpadaṃ paññattaṃ. Kacci nu kho mayaṃ pārājikaṃ āpattiṃ āpannā”ti. Bhagavato etamatthaṃ ārocesuṃ. “Āpattiṃ tumhe, bhikkhave, āpannā pārājikan”ti
On one occasion the monks from the group of six went to the dyers’ spread of cloth and took the dyers’ goods. They became remorseful, thinking, “The Master has laid down a training rule. Could it be that we’ve committed an offense entailing expulsion?” They told the Master. “Monks, you have committed an offense entailing expulsion.”
Tena kho pana samayena chabbaggiyā bhikkhū maraṇādhippāyā dāyaṃ ālimpesuṃ. Manussā daḍḍhā kālamakaṃsu … pe … manussā daḍḍhā na kālamakaṃsu. Tesaṃ kukkuccaṃ ahosi … pe … “anāpatti, bhikkhave, pārājikassa; āpatti thullaccayassā”ti.
On one occasion the monks from the group of six, meaning to cause death, set fire to a forest grove. Some people were burnt and died. … Some people were burnt, but did not die. The monks became remorseful … “There’s no offense entailing expulsion, but there’s a serious offense.”
(Here in first case the monks have committed an offense entailing expulsion)
There is no chance of remaining in monastic community after a pārājika offence. There cannot be a monk who is already defeated in the former (which ever it is) story. This is not the only issue to claim the fictional nature in the vinaya. There are almost all the possibilities of vinaya offenses covered in vinītavatthu.
Laying and amending the rules, giving decisions about vinaya issues may have consumed a lots of time. And there is no excuse given for being unaware about the rules, even where it was not that easy to send the information about new rules to farway places.
So there can be several possibilities,
- These occations are about several monks from the group of six
- Meaning of chabbaggiyā bhikkhū can be taken as few monks from the group of six monks
- There were several groups of six monks
- Due to an error
- Some of the characters and the stories in vinaya may be fictional