Hey Michele,
In Method, when you set a client up as a lead status, this user is kept out of QuickBooks. This is so that your company file does not fill up with lead customers and also for you to be able to track all contact prior to them actually becoming a customer. If you create the estimate in Method, you will be able to see lead status customers and use them to create estimates.
After you remove the checkmark for "lead status only", this client gets pushed into QuickBooks because they are now considered a customer.
A better way to go about this would be to create estimates in Method.