I agree, it falls slightly short of yuri. Certainly it lays the groundwork for yuri, and if there were another chapter it would have been able to easily go there. Just...not yet.
I know this is rather late but to me the whole point of the doujin was to illustrate the relationship between Shou and Nazrin. How Nazrin began as a simple supervisor to a close subordinate of Shou. Honestly the story itself already seems quite perfect in terms of length, with also enough parts to tell the way this relationship developed. To have yuri in this would feel kinda forced and may detract from the main plot point, not gonna lie.
Still love the story and art. Shou and Nazrin would always have a special place in me.