You can most certainly add an iCloud email address to Status Board– you’ll just have to do it manually.

Start by adding a new email panel to your board. Tap on Add email account then tap Other.

Now, you’ll need to add the server information manually:

Username
Your iCloud username (the first part of your email address before the @ symbol)
Password
Your iCloud account password
Folder
The folder you’d like to display
Display Name
This can be whatever you’d like to call this account
IMAP Server
Use imap.mail.me.com
Use SSL
Enabled
Port
993

Once you’ve added this information, tap Save.