Board Thread:General Discussion/@comment-11469381-20140408005123/@comment-16436805-20140503000338

PokemonmasterZ98 wrote: Donnie creates retro mutagen for Kirby & Splinter. WTF ! He promised to cure Timothy too! Dammit Donnie ! I think he's gotta unfreeze him first without killing him.

And I think as the mutagen makes Timothy stronger maybe exposing him to the retro-mutagen might not only make him human again but also kill him. We can't know for sure.