He might not even speak English...you can't automaticall assume this, after all this is a website like any other and can be viewed all around the world.
Now it is MOST likely people visiting here speak English, after all this is an English site. However, a small percentage do not, or they have English as a second/third/(other number) language. Not to say that people who have English as a second (or whatever) language are not good at English (far from it actually) but there are some in that category who are not fluent.