Yeah from what I can tell this is not a bug. tcllib and tcl are two different things, tcl is just the language we do not have tcllib.
It is not unheard of to not provide tcllib i.e Arch have tcl but tcllib is only available through the AUR (Arch User Repository).
If nothing in the repository requires it, no one has requested it and no one is offering to maintain it, it will not be added purely because it exists. So if you would like it considered for inclusion the first step is requesting it here.
Fun fact, apparently tcl is pronounced tickle.
