he got suspected for plagarism because of the way he writes
I'm more concerned that the student didn't review the work that was provided beforehand. If I were to order a paper, the first thing I would do when receiving it is read it. I would know right away whether it reads like something I would write or not. I would then make changes accordingly.
That aside, there are writers (like myself.. and no I am not trying to drum up business, just using myself as an example) who can change their writing style to fit different client needs. Some writers do not offer that type of service, and that is fine. We are all different and do things differently. For the most part, I do try to match my client's writing style when requested (within reasonable limits). By reasonable limits, what I mean is more in line with what @FreelanceWriter said: "All clients need to do is tell us how 'good' they want it for their level and that's exactly what they'll receive." ;)
Oddly, however, it is often more challenging to to write an ESL level paper than a PhD level. Why? Because a native English-speaking PhD level writer will have to spend extra time reviewing what he/she writes--whether along the way or after the writing is complete--and (for lack of a better term) dumb it down. I've had clients ask me to "make this not so smart" and that can be difficult. It takes twice as long, in some cases, to write, stop, read, reread, dumb it down, write some more... the same practice applies when simplifying after the paper is complete. It just takes more time and costs more $.