And Christ’s vulnerability doesn’t justify or condone the profanation, as some like to excuse as a matter of conscience.
Sin does not begin with the action…sin can be entirely interior.
Sin of betrayal can yes happen rather long before the action. The choice already being a serious sin.
This is one issue that is very divided among all believers. Cases are made for both sides. It’s difficult to know.
It is yes an exegetical and historical question. I would not say that it it is “very divided among all believers” -most never look into the question - particular because it has not really a bearing on anything today - but simply a question for exegets to discuss or write papers on.
I think if we knew that Jesus did in fact send Judas off without receiving, it would be more significant than if He gave to Judas. Because if He gave to Judas, it still would not have changed the fact that Judas was receiving unworthy (and adding condemnation to himself). But if Jesus did not allow him to receive, it is more of an action (or support for the action) for the Church to make a judgment about witholding Eucharist from people in serious sin. Though it wouldn’t condemn the practice of the Church requiring some with conspicuous and serious sins, since Judas’ was rather hidden.