Mustafa Ali was the first WWE talent to announce his departure from the company last month. This announcement came before the mass releases that affected both the main roster and NXT.
As a result, NXT had to make changes to its plans. Ali was originally scheduled to challenge Dominik Mysterio for the North American Title at NXT No Mercy.
However, Dominik ended up defending the title against Trick Williams instead and lost, making Williams the new champion.
According to Bryan Alvarez on Wrestling Observer Radio, the original plans did not involve Ali winning the title, so the decision to give it to Williams was made late.