I eat vegan food, but I also recognise that there's a distinction between someone keeping rescued chickens in a back garden, and keeping them in tiny cages or on the floor giant barns with no light in such crammed conditions that they start cannibalising each other (which are the conditions of about 90% of egg laying hens in the UK).

Even though I wouldn't eat their eggs, I can't really see the problem with having chicken around if they don't suffer. For people who eat vegan for ethical reasons, my impression is that suffering is the main concern.