President Barack Obama needs Hillary Clinton in the White House to safeguard his legacy. To that end, in the middle of the 2016 primary campaign, he endorsed her as the Democratic nominee for president.
In doing so, he effectively ceded his administration to Bill Clinton. Predictably, Bill Clinton inserted himself into the Obama administration, as demonstrated by his recent ambush of Attorney General Loretta Lynch at the Phoenix airport. I don't remember a former president ever interfering with the administration of a sitting president.
Bill Clinton's behavior in this instance is a good indicator of how he would conduct himself if he were to gain the White House again.
If Bill Clinton and Loretta Lynch wanted to have a "secret" meeting, they are both smart enough to meet outside of a public venue where everyone could see them.