Apple has introduced an appeal process for these kind of rejections. They could challenge the guideline.
"Additionally, two changes are coming to the app review process and will be implemented this summer. First, developers will not only be able to appeal decisions about whether an app violates a given guideline of the App Store Review Guidelines, but will also have a mechanism to challenge the guideline itself."
"Additionally, two changes are coming to the app review process and will be implemented this summer. First, developers will not only be able to appeal decisions about whether an app violates a given guideline of the App Store Review Guidelines, but will also have a mechanism to challenge the guideline itself."
https://www.apple.com/newsroom/2020/06/apple-reveals-new-dev...