Winning lottery and dying in your newly bought racing car, ok. Just dying, I do not see the irony.
But it might just be me, and probably as with taste one cannot really discuss that.
So the diabetic being killed by the insulin truck is ironic, because the contents of the truck no not in fact affect the lethality of being hit by it.
But the death row pardon coming in too late isn't ironic, because the pardon actually could have prevented the death. Whereas your example of 'Speedy' is ironic, because the nickname of the victim has no causal effect on the speed of the pardon.
Examples where the two oposed aspects of the situation actually do affect each other aren't ironic, they're just an ordinary conflict
To my mind a pardon that comes too late, or the lottery-bought racing car accident, are unfortunate but don't really hold a striking contradiction. That seems more significant than the causality.
It can be an acausual relationship (e.g. as in the classic observation "it's ironic how the bus always arrives just when you light your cigarette").
Or it can be a casual relationship (e.g. "A marriage councelor in an unhappy marriage" or the article's "the diabetic down on his meds, being run over by an insulin truck"- that is the very thing that he seeked and that would helped his health).
They don't need to be connected casually. They are, however, connected, by pertaining to the same subject and e.g. having contradictory qualities (in the example the pardon vs execution, plus the amusing timing).
>Winning lottery and dying in your newly bought racing car, ok. Just dying, I do not see the irony.
The irony being that you were served this great luck just before you got handed the ultimate unluckiness (thus rendering it all useless to you).
The irony in crashing in your newly bought sports car (or private jet) is in the fact that you were longing for a lottery win your whole life, hoping that it will bring you happiness, but instead it brought you death.
Dying for a reason that is not directly related to your newly acquired wealth is something different.
That's in line with the definition I found in the Cambridge Dictionary: "Irony - a situation in which something which was intended to have a particular result has the opposite or a very different result."