This property is a legacy option way back from Sun Solaris / OpenSolaris (yes, even before Oracle got its hands on it) and it only indicated that the vscan service should monitor this dataset - there is nothing else going on at the ZFS side.
You could basically re-implement that functionality by adding your own property e.g. scanme=off|on
, then have a service check this property and fire clamav every time a file on that dataset is read or written.