It's like a national shibboleth as impossible to get rid of as herpes.
Wouldn't it be weirder if he had no perceptible accent whatsoever?
I find it quite refreshing to be able to tell where someone is from, judging from their accent alone. When I was a kid, growing up in a rather rural area, I could tell with an accuracy of about 20km which area around my hometown someone I just met was from, just from by the fine differences in their accent. But in fact very few people like being identified like that.
I get it, breach of privacy and all that... but on the other hand, is it so bad to know where someone is from, when having a conversation with them
The real problem is of course the biases in people's head... "dutch people are such and such", and so on. I say we should fight the biases, not the fact that one's geographical origin can be guessed.