If Jesus had sinned, even once, His sacrifice would have been in vain
or his death as sinner would be merited, but, the waton quotation above in bold, does not assert that. It establishes, that the price (if really necessary for a non- existing debt*), would have been valid, whether the offering would be resurrected or not. It is after all the lost life, not the regained one, that is supposed to be so effective against the ravages of sins. so:
To really prove the point, Jesus should have been allowed to exist at least for 1000 years, without overlapping, because, according to the story, the first Adam lived nearly that long, dying short of a full [symbolic] day.
The idea that Christ, after paying the ransom, had to deliver it personally to the altar keeper, -really pushes the fancifulness of the whole script.
Ps: to be resurrected you have to die, by dying you pay the price for your sins, particularly involuntary ones! (and lets not forget you sin more** because of Adams sin/imperfection, for which you are supposed to never be held responsible). so:
*The flaws of all this runs deep, a fault line all the way to the story of the talking wolf ,--er-- snake.
** perfection obviously is not a barrier to sin , so imperfection no excuse either.