'as' has many functions. It can be used as you said, which would be in place of 'because'. But, if you notice, I just used it in my first sentence to mean 'like', which is probably more common than using it to mean 'because'. In the sentence you wrote, it is being used to show his position. You could replace it with something like, 'from the position of'. Here is another example of how it's used like your quote: "As CEO, I will improve profits and increase productivity." Notice that it is followed by a title in this phrasing.

The word "as" is very flexible in English. Don't rely on a single definition. When someone talks about his or her job, you might hear, "I work as an engineer." (for example) So, "as" indicates the job that person does.