To get a driver signed by Microsoft, the developer of the driver is required to provide a full cert pass log from the Windows Hardware Lab Kit to dev center [0]. Do you have any article that says the CrowdStrike driver has been tested by Microsoft?
To avoid going through the full cert process the sensor was certified but it loaded code from an uncertified module too so that it could be quickly updated to catch new threats. It's a tough corner to be in, to function properly it needs to update very quickly but the cert process takes a while to complete so they went with this work around of a signed module loading uncertified code.