You can get supported ruby 1.9.3 on RHEL6 or CentOS6 https://www.softwarecollections.org/en/scls/rhscl/ruby193/ or https://wiki.centos.org/AdditionalResources/Repositories/SCL
Unless they are unwilling to upgrade their rails and using the ruby version as an excuse :) Best of luck to you!
From the ruby193 SCL page you linked to:
"Community Project: Maintained by upstream communities of developers. The software is cared for, but the developers make no commitments to update the repositories in a timely manner."
But if you have a redhat subscription they are fully supported. I should have pointed that out in my first comment though, thanks for bringing it up :)
"All Red Hat Software Collections components are fully supported under Red Hat Enterprise Linux subscription terms of service. Components are functionally complete and intended for production use. " [0]
[0] <https://access.redhat.com/products/Red_Hat_Enterprise_Linux/...