Yeah, but that doesn’t mean every innocent person in prison for life is going to get exonerated before they die.
The argument that “the death penalty should be abolished because some innocent people are convicted” doesn’t hold any water because innocent people can be convicted with life imprisonment as well and die before being found innocent. Does that mean we shouldn’t sentence people to life in prison?
Which brings me back to my previous point: it’s acceptable to imprison innocent people for life, but not to execute them. At least in your minds.