But the "inside view" bias is not amenable to being repaired, just by being aware of the bias. In other words, yes, the suggestion is that the direct arguments are optimistically biased. But no, that doesn't mean that anybody expects to be able to identify specific flaws in the direct arguments.

As to what those flaws are ... generally, they occur by failing to even imagine some event, which is in fact possible. So your question to identify the flaws is basically the same as, "what possible relevant events have you not yet thought of?"

Tough question to answer...