A proxy study is able to show a certain side (1) of scientific "truth". There are caveats with proxy-studies.

Measuring oceanic currents show another side (2) of scientific "truth". There are caveats there too (see below).

Finally, one also could measure an oceanic current for a period of time and combine that data with a proxy study to see if the one study actually makes sense to the other (3). But particularly combining data from different sources has some serious caveats.

However. The question raised above by askod was whether the Labrador current can be measured directly. My answer: It can, but recent studies show one should tread carefully how to do that.

A snapshot study of measuring oceanic currents (that is, run a transect with a boat every x years and take a measurement every y meters) should now be considered a highly unreliable method to say something about the actual truth (whatever that may be). That is the core take-away lesson from the RAPID study and hullabaloo about the MOC shutdown: oceanic currents are fickle and their dynamics are unreliably mapped by a few years of snapshot measurements.

Secondly, no one here, myself included, seems to know at this point if the study actually included oceanic current measurements - snapshot or otherwise - or combined data sets. I will give it a look if it has.

Yet if we know that a certain methodology (snapshot measurements) is insufficient to properly capture a side of scientific truth, coalescing the data would not be of any help to learn us something extra.

None of this invalidates the proxy-data (1) in any way.