I am sorry that you were not satisfied with your meal choice, and as others have pointed out, fish is also included in KSML special meals, so I hope your plan does not leave you food-less again.
Whilst this passenger may not have had "Status", no one can be aware of the circumstances that lead to this person being sat in the Club Europe cabin. For all any of us know, he could have been on a full fare ticket, booked at the last minute for whatever reason.
I do hope the Executive Club reply to your e-mail/letter, and it may be an idea, if you continue not to eat fish through choice or medical reason, to speak to the crew before the meal service begins to possibly avoid this situation in the future.
On a separate, but still related to this point... It has been voiced quite vocally on here of the lack of consistency when delivering the Club Europe service, in relation to starting the service from the front row, due to the most important passengers being seated there. On this occasion, it was stuck to, and lo and behold, everyone is still not happy.