Fuse was recently enabled whereever LXC is enabled:

  commit 34783a9e
  Author: Jiri Denemark <jdenemar@redhat.com>
  Date:   Fri Feb 9 13:42:50 2018 +0100

    spec: Enable fuse only if LXC is enabled

Unfortunately the version of Fuse in RHEL-6 is too old for libvirt's
needs, but we still have LXC enabled there.
Signed-off-by: NDaniel P. Berrangé <berrange@redhat.com>