Hey, we're just reciprocating. If Haskell (GHC) can use Perl to bootstrap itself, we can use Haskell to bootstrap Perl 6. :-)

Seriously though, the plan for as long as I've known has been to write an implementation of Perl6 that is enough to start writing the Perl 6 compiler in Perl 6. So, the "haskell layer" is just part of the bootstrapping phase and most people won't be aware of it because it'll be long gone by the time they get to running actual Perl 6 code.