There's a whole thing about politics that I find quite distasteful, which is when people simply sling arguments at others because what they say is socially unacceptable, despite the fact that they themselves think it or express it in other ways.
The fact is that Belgium has long been the butt of many jokes by comics of many different political persuasions in the UK. The old meme of "Name 10 Famous Belgians" exists because people think it's a bit of a non-country (I can generally get to 8). It doesn't have the romance of France, the outward liberty of the Netherlands, the glamour of Switzerland. If someone of the cultural left had called it a non-country because of little more culturally than Technotronic and Tintin, this would have been considered as wry observation. But because Nigel Farage said it, people will point and call him a "little Englander" or the all-too-obvious "racist".
Personally, I've been defending Belgium for years because it makes great beer and food (but I'm biased in that regard).