To your point on differing cultures — absolutely our different contexts will inform what discrimination looks like in action.
For instance, in the USA where I am from, an action that demonstrates level one might be a shop owner refusing to bake a cake for a gay wedding. That is one of the strongest ways that you can show your intolerance to LGBT people in America - refusing service.
However, in other countries of the world, Level 1 may be demonstrated by holding to the death penalty for LGBT people.
Thus, I believe that this scale is applicable to any country and any context, but this will absolutely socially play out differently everywhere.
Somehow I had missed this, but you are right that same level of homophobia can be visible in very different ways in different cultures. Both can feel just as bad and react in different ways.