Works fine for me. Any architecture-specific bug would be more than surprising seeing that this is a python script that parses some files
commit eab013c718368c21b51f5bf56710a9711d1cb9f4 Author: Sam James (sam_c) <sam@cmpct.info> Date: Thu May 21 10:41:27 2020 +0000 app-portage/portpeek: arm64 keyworded (bug #721538) Last arch. Closing.