Sanghamitta wrote:modern sensibilities would put us at odds with the Buddha.
It is not uncommon, in my experience, to find modern sensibilities at odds with the Buddha. The Buddha of the scriptures was not as much of a fluffy bunny as some modern spiritual teachers would suggest.
Sanghamitta wrote:If any of us advocated sweeping someone off the forum like rubbish because they were not living up to our standards we would be suspended and quite rightly.
I have been a moderator of more than one Buddhist forum and I can tell you with certainty that people were "swept off the forum" all the time. However, it was never done lightly nor quickly but only after much consideration. Likewise, I don't expect the Sangha was too rough with each other over minor transgressions, but rather only when someone repeatedly showed themselves to be stubborn and untrainable.
As for the above sutta quote...
"After I am gone, the monk Channa should be given the brahma penalty."
"What, lord, is the brahma penalty?"
"Channa may say what he wants, Ananda, but he is not to be spoken to, instructed, or admonished by the monks."
- DN 16
Here we can see a specific example of "sweeping out the rubbish". And yet the story does have a happy ending. Cv.XI tells of how news of the brahma-penalty shocked Channa to his senses. As a result, he changed his ways and eventually became an arahant.
I am reminded of another sutta... AN 4.111
Kesi the horse trainer: "If a tamable horse does not submit either to a mild training or to a harsh training or to a mild and harsh training, lord, then I kill it."
Buddha: "If a tamable person does not submit either to a mild training or to a harsh training or to a mild & harsh training, then I kill him, Kesi."