You're right! I did type it incorrectly when I first asked the question. The original is this:

@^T = qw, 3( 2 9 6);
21_PENGUINS, and print map {(lc((split//=>\"\"=>")[$^T>1])..__)[$_]}@^
+T
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Which, of course, answers my third question: it is obvious that split is operating on \"aString".

While I was searching for the orignial, I also found some commentary on this little proggie. In fact, it looks like somebody else had the same problem I did, the __. How does 'c' .. __ create an alphabet generator? What's going on?