Take a look at this solution:
https://bigfix.me/fixlet/details/3870
In the comments section is the author’s description of the fixlet:
This fixlet is used to fix the patching issue that we have had with RHEL 5 and reboots. When using the internal BigFix reboot in the action tabs it does not properly clear the /etc/nologin file. This fixlet will add a check to delete that file on boot.
Also, it looks like question as already answered on forum here
And, take a look at this APAR and consider upgrading your clients to BigFix version 9.2.7+