From the frontspiece of this book.
Ishim ve-Shitos once showed another picture of R. Moshe Kunitz, namely this one:
He wrote בן יוחאי, in which R. Ya'akov Emden's aspersions on the age and authorship of the Zohar are attacked and the traditional attribution to Rabbi Shimon ben Yochai is defended.
In Dan Rabinowitz's article on dots, he writes:
"In fact, R. Simeon Sofer (1842-1906) writes that his father, R. Moses Sofer (Hatam Sofer) had wistfully hoped the authorship of these two works could have been reversed, i.e., with R. Emden defending the Zohar from the attacks on it by R. Kunitz."
I am not sure where to [sic]; either the dates are wrong, or it was another son, or a grandson who reported this, since the father died in 1839, the son was neither born in 1842 nor died in 1906 (I believe the correct dates are 1821-1883 ). Unfortunately the source, "M.M. Krangel, Shem haGedolim haShalem, Shearit Tzion, Podgorze 1930, s.v. Zohar" is not accessible to me at the moment.