My understanding was that in the Greek Language, "Once" may actually be interpreted as an ordinal.
equivalent to our "first". Using that as first instead of once, "after that" makes for a different sense then.
It may be that it is an assertion that God's judgement is guaranteed AFTER death... and not before.
Order of the appointments, death then judgement, not quantities of either.
Furthermore it may be saying that we all have an appointment with death prior to judgement. Then we have a problem with the NON death of Enoch... who did not die perse, but God just 'took him'.