There's nothing you can do to make it impossible to manually perform a Send/Receive on a specific account. What we are doing here is making it so that Outlook does not check for e-mail on that account when doing normal Send/Receive for "all" of the accounts. We're excluding the account from being included. That way when you press F9, Outlook will not check that account for e-mail. When it performs its regularly scheduled Send/Receive, it will not check that account for e-mail. When it checks for e-mail at the startup of Outlook, it will not check for e-mail on that account.
So, don't test it by performing a Send/Receive on that account only. Test it by just using Outlook as you normally do. Test it by sending yourself a test e-mail and then see if you ever get it. You shouldn't because that account is excluded. I mean, look at what you're excluding it from.