in your case the CompanyContacts is a collection field, and projections of a collection field is not supported yet. The other case you mentioned is about projections of scalar values. The only logical result set in your case would be a list of lists; I'm not sure that's what you want. The quickest way to access the collection content is to do a 'from c in scope.Extent<Company>() select c' and use a proper fetch plan in order to have the generated query join in the needed CompanyContact instances.
the Telerik team