Heterozygous FH will typically put someone at a total cholesterol roughly around 500mg/dl, and homozygous will get them closer to the 1000mg/dl mark. Dietary factors for most people will affect their lipids up to +/- 40mg/dl, and medication is generally required for anything beyond that.
For the gentleman with cholesterol nodules, that’s a not-unheard of symptom of homozygous FH and the associated cholesterol levels. I’m sure his diet is exacerbating it, however I would be genuinely surprised if that were the primary cause of his count being > 1000mg/dl. (With homo-FH and an extremely restricted diet, he’d still be unlikely to get below 900mg/dl)