this work doesn't seem to be anything fundamentally new. It just seems to be rephrasing of existing ideas. However if it can help people understand entropy then I think it's a quite valuable rephrasing.

Sean Carroll seems to think otherwise, judging by the abstract:

We derive a generalization of the Second Law of Thermodynamics that uses Bayesian updates to explicitly incorporate the effects of a measurement of a system at some point in its evolution.

[...]

We also derive refined versions of the Second Law that bound the entropy increase from below by a non-negative number, as well as Bayesian versions of the Jarzynski equality.

This seems to imply that this is a genuine research result, not just a didactic exposition. Do you disagree?