Strzok -- No Really -- Strzok

High level FBI agent Peter Strzok who led the investigation into Hillary Clinton's private and unsecured email server and who also was lead FBI agent working for the special prosecutor Robert Mueller is no longer on the job.  He was reassigned to work at Human Resources last Summer when text messages were uncovered between Strzok and another agent that were very anti-Trump and pro-Clinton.  Strzok was having an affair with a fellow agent assigned to the Clinton email investigation and they texted each other about political events of the day.  The texts were all stridently anti-Trump.  To say the least, that harsh anti-Trump and pro-Hillary position is a problem when Strzok was leading the investigation into Hillary's email mess.  The texts were discovered by the Inspector General who brought them to the attention of Mueller.  Strzok was removed from the team and sent to the FBI's version of Siberia.

Two questions arise here:

How could the FBI not know about Strzok's political views that he was expressing to his mistress?  Almost certainly, those around Strzok knew his views.  So does that mean that the problem was not his one-sided views but rather that he put those views in writing and got caught?

Second, why has it taken five months for the news of what happened to leak out?  Shouldn't the FBI or the special prosecutor have announced the personnel change?  Aren't the American people entitled to know that the guy who headed the Hillary investigation was seriously biased?