Some have theorized that this was why; there may have been other reasons as well:
"U decide - NYPD Blows Whistle on New Hillary Emails: Money Laundering, Sex Crimes w Children, etc...MUST READ! http://truepundit.com/breaking-bombshell-nypd-blows-whistle-on-new-hillary-emails-money-laundering-sex-crimes-with-children-child-exploitation-pay-to-play-perjury/ …": General Flynn (citing this article about Anthony Weiner: BREAKING BOMBSHELL: NYPD Blows Whistle on New Hillary Emails: Money Laundering, Sex Crimes with Children, Child Exploitation, Pay to Play, Perjury (11/02/2016))
"Flynn is his father's chief of staff and top aide. The elder Flynn pushed a conspiracy theory a week before the election that Clinton was involved with sex crimes involving children.": Son of Trump's incoming national security advisor pushes conspiracy theory targeting pizza parlor (12/05/2016).
All that info is shocking, to be sure.
However, remember Flynn was to replace the execrable Susan Rice.
Nobody but Pres Hillary was EVER supposed to see the dirt Rice and the Halfrican left.
Hillary was supposed to sweep it under the rug. The Halfrican had to be protected.
So a jihad against Flynn was launched to thoroughly discredit him.
The perfect scenario (for them) was to make sure anything he uncovered would seem unbelievable.
But this is the Gang That Couldnt Shoot Straight——so Flynn got indicted, on top of it all.