References specifically for the current definition of OHP should definitely originate from its formal definition or later, so Bilby's removals were indeed useful. On the other hand, if they are supporting the relevant point that academic publication in the modern field of OHP occurred before some start date, they should probably stay. (The field was defined at some point, but work in the area was done before then.) Such references would be particularly though not exclusively relevant to the history and origins of OHP.