I read your speculations about what was discussed and what not according to the leaks’ charges.
“How is your candidate’s campaign doing, Senator?” “Things are going well, Mr. Ambassador?” Does not qualify as any significant conversation and requires little or no notification to anyone including one requiring forms designed to entrap those filing them out if desired.
Now “Mr. Ambassador, I would like to get some help for Mr. Trump. Can you get some rubles and borsch from Vlad?” Such nonexistent conversations should spark concern.
To be clear, I have no speculations as to what particular aspects of the Trump campaign Loose Lips Jeff discussed with the Russian ambassador. All I know is that when the leak appeared, and Sessions understood that the contents of the discussion had been relayed to the Kremlin (and recorded), he recused himself immediately.
So either Jeff recused himself without necessity, hanging Trump out to dry, OR he recalled enough of the conversation to know that recusal was absolutely required. Neither case speaks well of him.