COPYRIGHT in the package's tarball says: The author hereby grants permission to use this software at no cost. This software is provided on an "as is" basis, and the author has no obligation to provide support or enhancements. The author is not liable to any party for any damage arising out of the use of this software. This neither grants the right to redistribute nor to modify the software, therefore it doesn't qualify as a free software license. However, it looks like this software is now maintained within tklib and distributed under a BSD like license; tkpiechart version 6.6 is included with dev-tcltk/tklib-0.5. We could ask the author if the BSD license applies retroactively to version 6.5 too. (Note: dev-tcltk/scwoop is by the same author and under the same terms.)
Fixed.