Have a look in the Vegetarian Diet section of the forum, which migh give you some food ideas for him - we do have a number of vegetarian (and vegan!) low carbers.
But some suggestions from my omnivorous low carb eating: nuts and seeds, nut oils and butters, avocados and avocado oil , olives and olives oil, full fat dairy - cream, cheese, butter, yoghurt? Veggies stir fried in various fats and oils instead of boiled, and served with various creamy or cheesy sauces. Berries and other low carb fruits served with double cream or yoghurt, and salads with full fat mayonnaise or oily dressings. Low carb bread, cakes, etc can be made from nut and seed flours, and would maybe help in that they are not going to look too fatty! Does he eat fish - if so salmon, mackerel, sardines are all nice and oily too. I think sometimes adding a little fat or oil to lots of different foods may be psychologically easier to accept than opting for great dollops of fats.
Our bodies apparently make most of our cholesterol anyway, so diet's not going to have any dramatic effects on that...
Robbity