Rakudo is by no means more official than any other implementation (for example currently niecza is quite strong, see https://github.com/sorear/niecza/ for the code).

Renaming Perl 6 to Rakudo makes about as much sense as renaming C to GCC to MSVC.

Rakudo, while a nice name, is also too easy to mistype - even core committers (me included) have frequently misspelled its name in commit messages etc.