Thank you for the suggestions.
Unless a lay teacher was trained in vinaya and could sort of culture from text- I don't think it could be much help. I am also not down with the Tulku institution, it is highly problematic and often political.
I asked a Theravadin monk who said he would ask his abbot, he didn't follow through.
I could ask a million people and get a million answers I am sure.
As someone who was ordained a novice, disrobed, and was told I could never ordain again but should live in robes and retreat I have formed a personal opinion I'd like to contribute to this discussion, as fun as it is to get to the written vinaya:
It is interesting to discuss how a bhikshu can and cannot be allowed to re-enter the community- when really it is so individual: to the person, the community, the abbot, the tradition, the monastery, the cultural and social ideals. Whether someone follows the vinaya 'to the letter', to the 'spirit', a mix, or to their cultural expectations. The vinaya, even how monastics live, has been changed frequently since the day the Sangha formed. Something in one community is okay but for another not. How schisms, sects, traditions etc...these all happened over difference in doctrine or practice.
Here is an extreme example with maybe a literal reading of vinaya and informed by a lot of cultural ideas that lead to an awful dehumanizing of a individual and their dharma practice. http://articles.timesofindia.indiatimes ... ons-buddha
A general example of change:
From what I have experienced the Tibetan traditions do not have a 'lifelong ordination' in letter but say it as though it is true in spirit- this comes about as a cultural idea and so it is a often seen as taboo for a monastic to disrobe (even properly) and ordain again. The person has failed to a degree. Unfortunately this attitude strips someone of their humanity and places the implied expectation that one must be morally perfect and free of desire, anger, ignorance to become and remain a monastic.
The South Asian traditions seem to encourage a temporary ordination as a merit making/personality development/coming of age tradition. Quite the opposite attitude. Perhaps choosing to be a monastic should be based on understanding of the path and dharma not as a social obligation?
Two extremes it appears and two cultures with a large monastic population and culture developed around that.
Were either of these attitudes or practices developed during and in place at the time of the Buddha? I don't know. Seems like they, in the same way as the vinaya, developed as an collection of actual situations happening in actual communities over time. Regardless of looking at the past or what was written...it will be always interpreted and rationalized in the context of the experience and history of the person applying it now.
At this point, to me, the answer to the thread question looks like:
Can a monk who disrobe reordain? depends, on a lot. Is a monk who disrobed (voluntarily or not) or expelled (voluntarily or not) face a huge block in their practice? yes. Does someone who never ordained face a huge block in their practice? yes. Does any monastic face a huge block in their practice? yes. Do lay people face a huge block in their practice? yes. Same delusions different expressions- desire, anger, ignorance are universal problems. Someone said: "Whether householder or monastic, your success is determined by making dharma your #1 priority in life".