I have reviewed your code and looks good to me. Can we change the message from "The database name is inappropriate" to some meaningful message, so that user should know why it is inappropriate. If user will be able to create database with "=" in name then why Backup, Maintenance and Restore fails.
I changed the messages to read more like this: "Maintenance job creation failed. Databases with = symbols in the name cannot be maintained using this utility.".
Changed.
However; I think that throwing the error when the user tries to execute the process is quite unhelpful, as the user may have spent some time choosing options etc. Can we do it when they open the dialogue (show the error instead of the tool's dialogue)?