Adjustment of Status - I-485

Hello guys, I just received my I-130 approval notice from Missouri Service Center and the language on it is very confusing:
it states:

"The above petition (i-130) has been approved. The petition indicates that the person for whom you are petitioning is in the United States and will apply for adjustment of status. The evidence indicates that he or she is not eligible to file an adjustment of status applications. This determination is based on the information submitted with the petition and any relating files."

"Because the person for whom you are petitioning is not eligible to adjust, we have sent the approved petition to the Department of State National Visa Center (NVC), NVC processes all approved immigrant visa which consular post is the appropriate consulate to complete visa processing. NVC will then forward the approved petition to that consulate. This completes all USCIS action on this petition. If you have any questions about visa issuance, please contact NVC directly. Please allow 90 days before contacting the National Visa center regarding your petition. The NVC will communicate with the person for whom you are petitioning concerning further immigrant visa processing steps. "

This is very strange bc the beneficiary had a valid M1 status in the United States although overstayed his visa and filed the both applications together and approved but I 485 case is reopened for reconsideration after approval.
Anyone from MSC or elsewhere has received a similar message on their NOA2?

My question is that if the beneficiary was not eligible to asjust, why did USCIS accpet the I-485 application and ask the beneficiary to go and do biometrics and had our interview in US and after approval of i485 case was reopened.

This does not seem to make any sense at all....