No he did not retire to take a lucrative job. He could have done that earlier or later. That was not his reason because that lucrative job did not last as he soon returned as a NY public safety official.
“I feel very melancholy. It’s been my life, this job.”
http://www.nytimes.com/1997/12/10/nyregion/fbi-s-kallstrom-head-of-flight-800-inquest-to-retire.html
He was forced out because he was a conservative among Clinton’s high-ranking officials, he was disgusted at the Clinton’s callous and abusive treatment of law enforcement, and repulsed by the blatant lies and corruption of the Clinton White House. Contrast that with Andrew McCabe’s lies and corruption to aid Hillary Clinton to win the White House and to entrap President Trump. They are polar opposites.
James Kallstrom is old school honorable, full of integrity, never wavering from meeting and enforcing standards of conduct and professionalism.
When people read in depth as I have about his thoroughness in the TWA 800 investigation, there is no lead investigator that could have done more. He met with all the victim’s families, he appeared in more than 90 news conferences, he prolonged the investigation to thoroughly get as many facts as possible, and he was criticized for taking too long including time and money spent on looking into sabotage, missile attacks. He looked into everything. He left no stone unturned.