Secondly, and I'm sorry, but your characterization is incredibly sloppy. The overall outcome is better if even one exoneration happens and you assume equal preference for life imprisonment vs execution. However:
* Many wrongful convictions will be exonerated. There are multiple per year. There has been at least one this year: https://deathpenaltyinfo.org/innocence-cases#CliffordWilliam...
* Further, while the preference might not be "infinite" you can just look at the overwhelming majority - innocent or not - of death row prisoners that exhaust all avenues of appeal to see that there is a strong preference there.
Secondly, of course I don’t dispute that there’s generally a preference for life imprisonment over execution.
From the perspective of the - potentially falsely - accused, "The difference is that you’re still alive" is a pretty fundamental distinction and "The finality of imprisonment and execution are the same" is false.
I think the reversibility argument is a sloppy way of trying to say that there is some massive difference in kind between a lifetime of imprisonment and an execution. The argument seems to be implying that outright ending a human life is taking infinite value, but imprisoning someone for an entire lifespan is taking only finite value. That's the only way it would make sense to allow for the possibility of some erroneous lifetime imprisonments, but not allow for the possibility of some erroneous executions.