The ActivityHistory and OpenActivity objects are actually available for use in Skuid (or in any Visualforce custom development) – Salesforce exposes them via the API, but they cannot actually be used except for within Salesforce internal code. Instead, do separate queries on the Task or Event objects. To just get Open Tasks, add an “IsClosed != true” condition, or to get just Completed Tasks, do a Condition with “IsClosed != false”. (I think that in a future release of Skuid we may make it so that these objects don’t show up in the list of possibilities, since they don’t support querying or any of the CRUD operations).
