Question about the circumstances of apparent causality violation due to objects with negative ADM mass

In The Generalized Second Law implies a Quantum Singularity Theorem, Aron C. Wall asserts that an object with a negative ADM mass would produce a "Shapiro advance" rather than the traditional Shapiro delay, and as a result could be used to send superluminal signals.

As a result of this, if a signal is sent from observer A to observer B, and passes near an object with negative ADM mass, then the response from observer B could be used to violate causality if there’s a sufficient relative velocity between the two parties.

If the same process as above takes place near the surface of a massive planet, where observer A is much closer to its surface than observer B, and the negative ADM mass is much less than the mass of the massive planet, could observer B’s response still be used to violate causality in the frame of observer A?