Isn't this just the second time such a feat has been accomplished?
Maybe not the second, if you count 51 Sagittae B (first brown dwarf discovered around a sun-like star, in 2002, directly imaged) and 54 Piscium B (from 2006, also directly imaged). Spectral types G1V and K0V, respectively, with true masses of ~50 M_J for both objects. But I can see why such a high mass would cause these sub-stellar companions to be sort-of ignored. I guess it all depends on perspective. Epsilon Indi also has a pair of imaged brown dwarfs.
According to recent papers on the current theories, which the authors admit are incomplete, tidal interactions of a planet with its host star allow mixing of the stellar interior. This lets lithium descend deeper into the star than possible without the presence of a planetary companion. The lithium gets roasted alive and no longer shows up in stellar spectra.
The lithium anti-correlation is only applicable to a very narrow temperature range of about 100 K on either side of the temperature of Sol. M, K, F and A stars do not seem to have this trend (the population of planets around A stars is mostly inferred from the detection of planets around stars that have evolved and cooled to become cool giant stars, while too few planets are known to exist around OB stars).
Interestingly, sun-like stars with close stellar companions do not seem to have this anti-correlation. If stellar mixing is the cause, then one would expect stellar companions would do better at that than planetary companions. The orbits of close stellar companions are statistically indistinguishable from the orbits of planetary companions.
Another idea is that a star will magnetically interact with its protoplanetary disk and somehow allow the lithium to be transported deeper into the star and destroyed that way.