I can't give you the answer, but I can give you an example of a Perl that can't handle the shebang line in the POD.

Our UNIX servers happen to have Perl 5.6.1 installed, so I fed your code to it. The process exited without emitting any output (despite the print statement), with exit code 0. This is in contrast to, for example, Perl 5.10.1 (which I have installed locally), which printed "hi" to STDOUT, as expected.

Your node made me curious, so I spent some time checking the perldelta's from 5.6.1 on, as well as the changelog for Pod::Parser, but I couldn't find a clue as to when the behavior was fixed.