I think difference in date of birth (1922 vs ~1960) is less important than difference of date of publication (2003 vs ~2015).
On the Outside View, is criticism 12 years after publication more likely to be valid than criticism levelled immediately?
I do not know. On one hand, science generally improves over time. On the other hand, if a particular work get the first criticism after many years, it could mean that the work is of higher quality.
Something you are not taking into account is that Chapman was born a lot later, Any undergraduate physicist can tell you where Newton went wrong.
I think difference in date of birth (1922 vs ~1960) is less important than difference of date of publication (2003 vs ~2015).
On the Outside View, is criticism 12 years after publication more likely to be valid than criticism levelled immediately? I do not know. On one hand, science generally improves over time. On the other hand, if a particular work get the first criticism after many years, it could mean that the work is of higher quality.