Hans Kung had a better reason to criticize Pope Benedict's exercise of power.  During Vatican II BOTH Hans Kung and Joseph Ratzinger were periti for Cardinal Joseph Frings of Cologne, Germany.  As Vatican II was concluding, Ratzenger---was offered a position at Tubingen [because of the kindness of Hans Kung].  Tubingen was the most prestigious and erudite university in Germany.  But the end of the Council came during the turbulent late 1960's and early 1970's.  While Kung was not afraid, was able to think on his feet and handle a lively give-and-take with both students and faculty, Ratzinger was not.  As usual with Ratzinger, when his beliefs and his authority were challenged---he didn't dialogue---but went to form a new generation of docile, non-thinking theologians at Regensburg, which he helped to establish.

When Ratzinger became head of the CDF, under JP II, he did not stand up for his former colleague, Hans Kung, and said nothing when Kung was silenced by JP II.