According to Ancestry.com's pop-up description of this database, it was uploaded in 1998 and has not been updated since then.
You have probably put your finger on the source of this purported "census" item -- a list of names from the published Philadelphia passenger lists' index together with year-dates.
Ancestry.com has a lot of such poorly compiled and barely described databases. Don't ask me about the purported Delaware marriages index that thankfully was removed a few years ago. In this case, all of the crucial data has been stripped away from the database (nature and title of the source, particulars as to date, embarkation and arrival points, ship name, etc.).
These approaches to source records are very confusing for all but very experienced researchers, and contribute to discouragement.
Recently Ancestry.com stripped away actual document-type descriptions and component names from its extracts of the Sussex County, DE Calendar of Wills (a mistitled book in any case) -- which includes abstracts of a large variety of estate documents in addition to wills. So now those who run across these entries think that thousands of persons who died in DE before 1801 made wills, who did not leave wills. Those who take the next step and try to obtain copies of such documents from the DE Public Archives will encounter Archives staff who may by now be frustrated and peeved by inquiries insisting that the nonexistent document must be there somewhere because "Ancestry says so."