You seem to be saying that given a set of very unusual requirements which Perl is obviously ill-suited for, you would use a specialized tool instead. I don't see how anyone could disagree with that. But the original poster didn't have these specialized requirements. He was concerned about using Perl to build a high-quality system. There is no problem with using Perl to do that.

I also believe that the Java project you refer to stands a good chance of spending millions, taking years, and producing something unsatisfying, regardless of the language chosen. I don't think Perl is going to make it any harder to write than Java. (Java in a totally fault-tolerant system? That's madness.)