> Tcl_Finalize can be called more than once, says the tcl doc.

I take that to mean that when calling Tcl_Finalize more than once, the second and following calls will do nothing rather than crash the process, corrupt memory etc.

The Tcl docs are quite clear that Tcl is no longer usable after calling Tcl_Finalize.  Therefore, E. Paine's latest comment appears to be correct in the sense that we can't call Tcl_Finalize when cleaning up a tkinter.Tk instance.  The same goes for Tcl_FinalizeThread.