I have a different solution for you and have seen this and addressed this in my environment. When you add a user to ESX using the useradd command also issue this command
/usr/bin/chage -M 99999 username
This will keep the password from expiring on the ESX side
Steve Beaver
VMware Communities User Moderator
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Co-Author of "VMware ESX Essentials in the Virtual Data Center"
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