That module only "works" if the flow of the program actually fetches $&. The following program has $& in it (and hence, penalties occur), but the FETCH is never triggered:

#!/usr/bin/perl

use strict;
use warnings;

use AmpKiller;

"foo" =~ /o/;

if (@ARGV) {
    print $&, "\n";
}

print "The End\n";

__END__
The End
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Abigail