IMO I don't think we need to go that far, because 1) the new functions are provided for FDW authors only, and 2) we don't make changes to the stats that often.
That would be simpler, to be sure. However, in the past I've received pushback on functions that had a large number of parameters, and this would definitely be a large number of parameters, approximately 17, so I thought I should at least offer the variadic way.
