Your "TL;DR" is ... a bit off.
They made two small errors in handling the O2 figures. As a result, they
slightly overcalculated the warming (not "vastly"), and
underestimated (not overestimated) the uncertainty.
Note from co-author Ralph Keeling Nov. 9, 2018: I am working with my co-authors to address two problems that came to our attention since publication. These problems, related to incorrectly treating systematic errors in the O2 measurements and the use of a constant land O2:C exchange ratio of 1.1, do not invalidate the study’s methodology or the new insights into ocean biogeochemistry on which it is based. We expect the combined effect of these two corrections to have a small impact on our calculations of overall heat uptake, but with larger margins of error. We are redoing the calculations and preparing author corrections for submission to Nature. (Emphasis added)
The article will be updated soon. In the interim, a more in-depth explanation is here:
Resplandy et al. correction and response « RealClimate
The projections changed from this:
View attachment 67244270
To this:
View attachment 67244271
We should note that these types of errors are
not common, and that most models are fairly accurate.
And of course, we should note that two minor errors in one paper, that aren't even serious enough to radically alter the conclusion (let alone require a retraction), does not exactly send the entire edifice of climate change crashing to the ground.