That chart isn't the best way to present their argument, which is "Climate change is a good thing because it leads to fewer temperature related deaths." They should show use a bar chart instead.
However, if you're going to make the argument that climate change is saving lives, you shouldn't constrain yourself to temperature related deaths. To make that argument, you'd have to account for all causes of death related to climate change.
That chart isn't the best way to present their argument, which is "Climate change is a good thing because it leads to fewer temperature related deaths." They should show use a bar chart instead.
However, if you're going to make the argument that climate change is saving lives, you shouldn't constrain yourself to temperature related deaths. To make that argument, you'd have to account for all causes of death related to climate change.