I solved the issue.
It was SELinux after all.
I ran "sealert -a /var/log/audit/audit.log | less" and saw that SELinux was denying httd write permissions to the /etc/httpd/logs/manager.node.nodes.lock file. So I temporaryly enabled it by running the following two lines
"grep httpd /var/log/audit/audit.log | audit2allow -M mypol"
"semodule -i mypol.pp"
I then went and removed the locks
"rm -f /etc/httpd/logs/manager.node.nodes.lock"
"rm -f /var/lock/subsys/httpd"
and then resstarted httpd ("service httpd start")
That did the trick. I still see some errors in the log but at least for now httpd is running and I can see the mod_cluster-manager page.
Your fixed did not work out for me, this def worked:
getting [emerg] create_mem_node /etc/httpd/logs/manager.node failed: Permission denied Configuration Failed when starting apache on rhel 6 after mod_cluster is addedhttp://docs.jboss.org/mod_cluster/1.2.0/html/faq.html#d0e5409
thanks to jfclere