I am sure that the short answer will be something like; Squirrels Reflector Library is a closed source / proprietary library and Kodi as GPL licensed open source program can not link with a proprietary library that is not a system library, and Squirrels Reflector Library certainly does not meet the criteria of a system library.
https://en.wikipedia.org/wiki/Free_and_o...e_software
Kodi is "free/libre and open source software (FOSS/FLOSS)" and Kodi's core code is licensed under GPLv2 and as such, as far as I know, unless it is a system library that can be linked, Kodi can practically only integrate libraries and code that are compatible with the GNU General Public License v2.0 license:
https://www.gnu.org/licenses/gpl-faq.html
https://www.gnu.org/licenses/gpl-faq.html#FSWithNFLibs
https://www.gnu.org/licenses/gpl-faq.htm...yException
https://www.gnu.org/licenses/gpl-faq.htm...atibleLibs
Presumably, only if you could somehow convince the Squirrels company that makes Reflector Library to non-exclusively re-license or dual-license it as GPL or LGPL could developers use it Kodi, as a "copyright holder for a program can release it under several different licenses in parallel. One of them may be the GNU GPL.".
https://www.gnu.org/licenses/gpl-faq.htm...erGPLAndNF
https://www.gnu.org/licenses/gpl-faq.htm...herLicense
https://www.gnu.org/licenses/gpl-faq.htm...ThirdParty