The "Kingdom exclusion" teaching was not originated by WL. Others authors before and after have penned similar conclusions.
Here is a recent book (2002) of a detailed view of reward and punishment at the Judgment Seat of Christ:
"The Believer's Payday"
by Paul N. Benware
"We now enter our study of the coming payday for the believer when he or she stands individually before the Lord who bought him or her and gives account for what was done in this present life. For some, it will be a day of incredible joy, satisfaction, and rejoicing. For others, it will be a troubling day of shame and even grief." Benware, Paul N. The Believer's Payday (p. 7). AMG Publishers. Kindle Edition.
https://www.amazon.com/Believers-Pay.../dp/B006T37ICK