Hi Mike,
I can reproduce this problem. Noticed it on Tuesday actually but didn't have time to check out the reason for sssd failing. Changing the permissions in the .py files is the right fix for this.
As for why it clobbers it: The sssd.conf is generated on the headnode according to the configuration of the node. It is then written by qluman-execd on boot or when you write Nameservice Config later. Qluman-execd only has a command to write a file with content, owner and mode. There is no modify or update mode. It always overwrites any existing file. So if it gets told to set the wrong mode you get the wrong mode.
Hope that explains it a bit. Goswin von Brederlow