With regard to the MalwareBytes threats, that appears to be a Windows only listing. I should also point out that Silver Sparrow is not technically a threat and there is no evidence it ever was.
The macOS Silver Sparrow write up is here
https://blog.malwarebytes.com/detections/osx-silversparrow/.And I can attest that MalwareBytes for Mac has been detecting the critical elements of this infection since at least last Friday.
The proprietary ClamXAV database (as differentiated from the ClamAV database) is not generally searchable, so not sure where you looked, but components of Silver Sparrow are currently detected by ClamXAV as either Trojan.OSX.Generic or Trojan.OSX.SilverSparrow.
