So, in planet Genesis orbit, Kirk made the last klingon prisoner. Promised to kill him later, but lied.
The novelization of ST IV claims he suicided in his Vulcan detention cell.
Pocket Books' first edition of "The Klingon Dictionary" claims he worked on the translations with Marc Okrand.
My fanfilm "Free Maltz" claims that Saavik set him free and he escaped as a stowaway on the Bounty
when it went to save the whales.
Pocket Books' "Genesis Wave" original duology of novels teams him with an elderly Carol Marcus to stop the rampant wave in the 24th century.