Kyle,
Yes, that parameter is not currently a valid token that can be used within the combo box SQL Options BUT... You can use all short field name values. In other words, you could make a hidden field called UserID and retrieve that userID either via the SQL option default value or better yet, you could just use whatever field you have specified for 'UserName'.
Give this a shot:
1. Make the short field name of your UserName field MyUserName
2. Change the query to get the UserID for that username
Example:
SELECT OrgName as QuestionOption, OrgID as QuestionOptionValue
FROM OrgTable
WHERE OrgTable.UserID= (Select UserID from Users where UserName = '$(MyUserName)'
This 'should' work, but it possible that the username field would have to be before the combo box in the order list.
If this doesn't work we will try and get the enhancement for adding the UserID parameter/token added in the next release.
-Chad