Only having Perl 5.10 is a problem, and it comes down to timing. 5.12 was released upstream in April, didn't get into Fedora until mid-June, by which point it had missed the deadline for entering RHEL 6 (because of the extensive QA that we would require).

If you're a customer and you need 5.12, be sure to open a support ticket and/or talk to your TAM.