That code disables the SSH service at the end.
But does New-SshSession actually work?
What is returned when you do

New-SSHSession -ComputerName MyEsx -Credential $cred -AcceptKey -Verbose

Does the ESXi firewall allow SSH traffic?
Check with

Get-VMHostFireWallException -VMhost MyEsx -Name 'SSH *'

Is the SSH session timeout set too short?
Check with

Get-AdvancedSetting -Entity MyEsx -Name 'UserVars.ESXiShellTimeOut'