My understanding is that the "limited periodic scanning" is a basic protection for home users that do not have a full AV service. It is not intended for enterprise use.
The enterprise model for MDAV is Defender for Endpoint (MDE). With MDE and Intune you can manage MDAV for the enterprise. Including local AV scanning, cloud-based analysis, and active vulnerability assessment. MDAV is also used for several blocking features for disallowed apps, malicious websites, etc. If a 3rd party AV is detected, it places MDAV into a passive mode. While in passive mode, MDAV gets updates, serves as a backup AV if the primary is disabled, and continues to provide a level of cloud-based analysis and vulnerability assessment. It may be possible to run MDE in active mode, side-by-side, with your non-blocking EDR.