You'd have to essentially embed a slow unoptimized APL in it which you can do. Add that to the fact that P6 is already slow at the moment would be an issue. Also, unlike APL, your P6 APL operators would probably be only known to you.
Unicode has APL characters, so create the operators using them.
If there is a conflict with an existing feature you could always create a Slang. A Slang is a module that changes the parser. (It could be argued that with this feature all programming languages are a subset of Perl 6)
I've heard that quote, but realistically, that would be a huge project to write an efficient APL in P6 and as I already said, the performance wouldn't make you happy.
