A low score in some categories is a good source to develop the person if he/she is hired. It is an excellent way to improve interviews since you can develop questions around the lower competency scores to get more detail from the individual related to situations they might have faced and what awareness they have about their abilities.
You have a head start on career development and also knowledge to know where the person might struggle in the job so you can give them support or work with the manager to coach the individual.
A low score doesn’t mean the person can’t do the job. It just highlights an area that might take the individual longer to work through, complete, or need some assistance until he/she can develop the competency by doing the job.