Thanks for posting your workaround!
(The reason the AdoHelper was configured for SQL Server is because that's the fallback when the data provider is unknown. The recognized data providers are System.Data.OleDb, System.Data.OracleClient and System.Data.SqlClient. Another workaround might have been to extend the existing OracleProviderHelper class, but since, as you say, this is largely undocumented, that might have proven more difficult than your very nice solution.)