You can make a work around for it by using /etc/profile file.
I added the following lines at end of /etc/profile. It will overwrite the actual umask command by after setting it the value which you require
umask 0002
alias umask='echo umask cannot be changed'
enable -n umask
[root@client1 ~]# umask
umask cannot be changed
[root@client1 ~]# \umask
-bash: umask: command not found
[root@client1 ~]#
You can make a work around for it by using
/etc/profile
file. I added the following lines at end of/etc/profile
. It will overwrite the actual umask command by after setting it the value which you require