I am not sure how this is evidence to justify his point. The gemora itself reveals by names that a number of scholars became impotent because of Rav Huna's lectures and in addition it concludes with Rav Acha who said that the whole group of 60 students became impotent except for himself. Why isn't that lashon harah according to the Ben Ish Chai since it was said about others? If it is permitted to relate this information about others than why should it be considered lashon harah when said about yourself?
Yevamos (64b): With regard to the assumption that ‘it is possible that it was he who was unworthy to have children from her’, is it not possible that it was she who was unworthy? — Since she is not commanded to fulfil the duty of propagation she is not so punished. But surely it is not so! For the Rabbis once said to R. Abba b. Zabda, ‘Take a wife and beget children’, and he answered them, ‘Had I been worthy I would have had them from my first wife’! — There he was merely evading the Rabbis; for, in fact, R. Abba b. Zabda became impotent through the long discourses of R. Huna. R. Giddal became impotent through the discourses of R. Huna;20 R. Helbo became impotent through the discourses of R. Huna, and R. Shesheth also became impotent through the discourses of R.Huna. R. Aha b. Jacob was once attacked by dysuria, and when he was supported on the college cedar tree a discharge issued like a green palm shoot. R. Aha b. Jacob stated: We were a group of sixty scholars, and all became impotent through the long discourses of R. Huna; with the exception of myself who followed the principle, Wisdom preserveth the life of him that hath it.