According to Ancestry's blurb on that particular databse.
Description:
This database contains the surviving service records of non-commissioned officers and other ranks who served in WWI and did not re-enlist in the Army prior to World War II. The type of information contained in these records includes: name of solider, age, birthplace, occupation, marital status, and regiment number.
So it could be that it either didn't survive or he re-enlisted.
Pauline