Reputedly, this word means a fear of dining in the social sense, and by association, of dinner conversation.
The opposite would presumably be something like “Δειπνοσοφιστές” (“deipnosophist”, meaning something like “master of dinner-table conversation”), which is an actual word used by Athenaeus as the title of his book “Δειπνοσοφισταί” (“Deipnosophistae”) written around 228 AD.
In any event, should Deipnophobia be a real rather than a “coined” condition, then sadly like laryngitis and nudism, it appears something never associated with the people you wish it were.
Literature & Lore
A Canadian filmmaker, Lewis Leon, made a 20-minute short in 2004 named “Deipnophobia.”
Language Notes
A coined word from two Greek words: “Δειπνον” (“deipnon”, meaning “dinner) and φοβία (“fobia”, meaning “fear”).