Hello,
In hybrid AD, the last sign in to AD doesnt seem that useful on its own?
Yes, that is correct as the property is not replicated among domain controllers.
Dont we want to see the last sign in to either AAD or AD?
The above response is only for on-premises AD as Adaxes did not have the feature for managing AAD by that time.
Of is the lastlogon time stamp synced in hybrid AD?
The property is not synchronized and thus account activity should be checked separately in on-premises AD and in Azure AD.