If he is thinking in English (as you are implying) then he is to the point of fluency. That happens often when someone is in a situation where they are forced to speak a foreign language nearly all of the time. And no, it does not make it a new first language, simply a second in which they are fluent.
Anyone who hates on Henrik and Phil for their language skills has obviously never gone out and learned a second language. No, not taking a couple classes in high school, truly learned.