I bet you anything this is what happened. That is why Flynn said he had a story to tell...
Quoting: A 55131602 If this is what happened, this is the reason the FBI hasn't granted immunity for him to tell it.
They are the story!
Quoting: Zen & Zi Logic is obviously not your stronger suit.
If Flynn has just implicitly confirmed that twitter poster's theory, that can only mean 1 of 2 things:
a) Flynn's a liar, or
b) Russians were indeed heavily involved in the U.S. presidential election process, spying on the Democratic Party members and sharing their intelligence with (chosen) Republicans (in Trump's camp).
The reason why only these 2 options are possible is because
no one shares their intelligence with anybody, unless they're directly involved in the whole process,
because sharing any intelligence always carries the risk of revealing your sources and methods.
The FBI must've reached the same conclusion.
Giving Flynn immunity under the option a) would be incredibly stupid. Giving it under the option b) would only be smart if he has any concrete evidence to give to the FBI... which he obviously either doesn't have (a), or is not being squeezed hard enough by the FBI to provide it (b).
It was a smart move by the FBI to deny him immunity and thus put him under greater pressure.
Though... if option b) is the correct one, the most likely outcome of Flynn's bluff will be him suddenly suffering "a tragic accident" of one sort or another... before he gets any chance to spill the beans on the higher-ups (his superiors) in this conspiracy to install Trump.