At the moment, you can create an enclave enabled key in a database that doesn't has an enclave.
I would expect that the PowerShell command returns an error message since there is no enclave enabled on the database.
This is not possible in SSMS for example.
When creating a column master key you can specify if the key should be enclave enabled or not.
$cmkSettings = New-SqlAzureKeyVaultColumnMasterKeySettings -KeyURL $akvKey.ID -AllowEnclaveComputations -KeyVaultAccessToken $keyVaultAccessToken
$cmkName = "CMK1" New-SqlColumnMasterKey -Name $cmkName -InputObject $database -ColumnMasterKeySettings $cmkSettings
At the moment, you can create an enclave enabled key in a database that doesn't has an enclave. I would expect that the PowerShell command returns an error message since there is no enclave enabled on the database. This is not possible in SSMS for example.