Edwin ,
It is interesting that you have trouble with the third person singular. Lots of people have trouble with this in English although the rule is very simple. The third person singular is the only person where the ending is different, yet people struggle. To me this just confirms that rules are not always that helpful. Your brain just fights the illogical nature of this rule. Either you and others will eventually stop making this mistake or the language will change and allow “he don’t”
As to the issue at hand, the issue is known as a “dangling modifier”. It is usually taught that the modifier, in this case the phrase “as a linguist” should be followed as soon as possible by the word being modified. This is largely a matter of style, as daw says. The concern is that if the modifier is dangling there can be some ambiguity.
“As a child, my brother was my closest friend.”
Who was the child, me or my brother?
I could have written " It is important, as a linguist, that you …" but instead I wrote “As a linguist, it is important…” You could argue that this is a dangling modifier, but there is no ambiguity.
No one will think that “it” is the linguist. The next possible “linguist” or person is “you” in the sentence. I could also have written " As a linguist, you need to …" in order to avoid any possible dangling modifier, and the meaning would have been similar, but not the same, since “you need” is stronger than “it is important”. I did not want the word “need” but rather the word “important”, so I wrote it the way I did (I guess since I cannot remember).
We often place certain words at the head of a sentence for emphasis. “Gone are the days” “Strange are the ways of men”
I really recommend watching the video that Alex posted on this subject.
One last point on possible ambiguity. This sentence is taken from a specific context. The full context also reduces any ambiguity. If we just look at this sentence in isolation we may not even know what the word “linguist” means in this context. However, anyone who is reading the book knows that if refers to the first meaning in the Oxford English Dictionary, that is " a person skilled in foreign languages."