Below is a patch to add firewalld to the base_pkg_erase var (used by base role).  Like the Fedora var, this will remove firewalld from RHEL systems and should fix the issue below.

From dc7c5dc38efab1873c43b6a5d85978d44843bc72 Mon Sep 17 00:00:00 2001
From: Brandon Gray <graybrandon@gmail.com>
Date: Wed, 5 Jul 2017 08:12:54 -0500
Subject: [PATCH] added firewalld to base package removal for rhel

---
 vars/RedHat.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/vars/RedHat.yml b/vars/RedHat.yml
index bd4c73c..3aff512 100644
--- a/vars/RedHat.yml
+++ b/vars/RedHat.yml
@@ -1,7 +1,7 @@
 ---
 dist_tag: el{{ ansible_distribution_version[0] }}
 base_pkgs_inst: []
-base_pkgs_erase: ['firstboot-tui','bluez-utils', 'sendmail']
+base_pkgs_erase: ['firstboot-tui','bluez-utils', 'sendmail', 'firewalld']
 service_disabled: []
 service_enabled: []
 is_rhel: True
-- 
2.9.4



That does bring up one more issue: You are using firewalld there and
aren't allowing our nagios/nrpe. I added a rule to allow port 5666/tcp.
You might also add this upstream/ansible.