That’s not true. The virus doesn’t magically seek out the liver. It has the ability to enter and reprogram several different cell types.
http://news.sciencemag.org/health/2014/08/what-does-ebola-actually-do?intcmp=collection-ebola
There are several articles that establish that the liver is a site of prolific viral growth. I think what might happen is that the shedding of virus from the liver causes the blood to contain a high number of viruses.
It is true that the virus infects a few different cell types, including cells of the immune system (which live primarily in blood). The preferences for different cell types depends on a number of factors, but is not equal for all of the cell types it infects.