I was referring to the changes they made to the compiler in their fork of clang, which makes the "catching up" with upstream clang challenging as they need to rebase.
They can still sell their IDE and runtime libraries.
What they're adding are non standard C++ extensions only used by C++ Builder (properties, etc). There might be little benefit (and just maintenance cost) to upstream those to Clang. Clang also moves fast while it appears C++ Builder is still at C++17 [0].
