That is not neccesarily true. For the most part (to my knowledge), evidence of flight is typically allowed into evidence. It is based on the theory that the D's consciousness of guilt motivated his flight and is circumstantial evidence of his guilt (see Hutchins v. Sleeniger). By definition all evidence is prejudicial, what is not allowed is evidence that is unfairly prejudicial. The fact that Mbakwe left town is evidence that he might have had consciousness of guilt. There certainly could be other explanations for Mbakwe's flight, but those can be attacked and explained on the Defense's side of the case.
It is important to note that this is almost a perfect case for the Prosecution to get the evidence of flight admitted into trial. Mbakwe left town immedietly following the attack (the further away from the crime the less relevant the evidence), Mbakwe wasn't done with school and wasn't expected in MN for a time (takes out some possible other explanations), and one could argue that Mbakwe would have not known about the attack had he not done it (by the time he left, had he already been contacted)?
Like I said, I am not going to pretend that I know what happened that night. However, the fact that Mbakwe left town in the manner in which he did, is certainly strong evidence that he had a consciousness of guilt. (like all evidence it isn't fool proof). But to pretend like the fact that there might be other explanations and/or it is merely circumstantial doesn't change the fact that it is still decent evidence.
However, to the poster I quoted. I think you might be mixing up a few principles. Evidence of Flight without anyother evidence is typically not allowed to be sufficient enough for a conviction in most jds (but not all), however, in Mbakwe's case there is other evidence (circumstantial about not coming home that night, victim's ID, etc.).
