I think SQ's catering out of Heathrow is done by Alpha LSG. Without being rude about them relative to Gate Gourmet, if one large flight kitchen can do a half decent Lobster Thermidor then why can another not do so if the client orders it?
The critical point about a Lobster Thermidor is that the meat is removed from the shell, chopped and mixed with the sauce, then replaced in the shell.
If BA claim that thing photographed above is a Lobster Thermidor, someone at BA needs to be moved to a role not involved with food.