Switzerland does not have a homogenous population, and to a reasonable person who has travelled in Switzerland I think this is an insane thing to be defending. A significant proportion of the population (certainly for Europe) do not even share a common first language. Significant proportions sit on different sides of the reformation which is again a big deal for Europe. etc
I think that it's pretty obvious that the user that you're responding to is using the term 'homogenous' as a euphemism for "white"
Homogeneous isn't likely the correct word. Shared cultural norms and "harmonious" is often more accurately what people describe when the call a country "homogeneous".