One quote I've always liked but that might be mildly offensive to some is "Those who don't understand UNIX are doomed to reinvent it, poorly." from Henry Spencer. It's not directly Perl-related, but it's close. Given the PCRE and so many other languages doing regular expressions as a bolt-on these days, perhaps "Those who don't understand Perl are doomed to reinvent it, poorly", but that could still be somewhat offensive.
I really like your security, optimization, and other quips and the references to xkcd. Most of those included that aren't attributed can be attributed to someone, and probably should be. I know one is commonly credited to Donald Knuth and another to Kent Beck.
Simple restatements of long-time Perl and PerlMonks slogans might help liven up the quips, too. "Orthogonality is overrated" could stand in for "TIMTOWTDI" or "There's more than one way to do things".
Some short and simple in-jokes among the community might work, too. "By Christmas", "Who has the pumpkin?", "Just Another Perl Community Website", "What was rule #1 again?", and "Is that Obfu, Poetry, or Golf?" come to mind.
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