Whopity
As I understand it, the Applied Instrument restriction is a UK CAA hangover. Come the EASA changeover, all FIs will need to get a IRI rating on their licence alongisde their FI rating if they want to teach IF. This is already the case in other European countries under JAR-FCL.
Those FIs who have removed the restriction based on an IMC or UK CPL/ATPL IMC privileges have paid lots of money to do the IRI course and gain those instructing privileges - there should be a mechanism so that is recognised, even if it has to stay dormant until an IR is obtained.