@tmcmillan99 regarding @Kevin-C suggestion regarding a contract, I would highly recommend including a license.txt file in your theme folder that specifies how the theme files can be used.
TXT files can’t be directly edited in Design Tools so it should lock it down automatically and it should only be accessible via the CLI - if that’s not the case, please let me know so I can test further to see why this behavior might’ve changed (and check with the developer advocates for further insight).