I don't doubt what you're saying, however I wonder whether the person you spoke to was misinformed.
Revalidations by experience are NOT a test or assessment of competence - they are merely admin tasks (from the FE's point of view). Therefore they are outside the scope of the
EASA Examiner Differences Document.
2.1.1. Purpose of the Examiner Differences Document
This document [...] is intented for use by examiners with a Part-FCL examiner certificate conducting a test, check or assessment of competence on a Part-FCL licence holder whose licence was issued by a competent authority (CA) other than their own.
Furthermore I point you to the Irish
Examiner Briefing Document which reiterates the blanket authorisation to foreign FEs:
11. An Examiner certified in accordance with PART-FCL is authorised by the IAA for the purposes of revalidating a Type, Class or Instrument ratings in an IAA-issued PART-FCL Licence according to the Examiner’s privileges.
and then goes on to list exceptions:
12. The renewal of an expired Type, Class or Instrument rating, must be endorsed by the IAA, except where an Examiner is specifically authorised by the IAA to do so.
13. The Revalidation or Renewal of an Instructor or Examiner certificate shall always be endorsed by the IAA.
If the IAA wishes to exclude revalidations by experience, they should have written so.