Talking to a Russian ambassador was neither a crime nor probable cause to believe that a crime was being committed. A citizen could meet with the Russian ambassador over drinks tomorrow without violating any law or creating probable cause to get bugged.
I don’t understand why so many different high level people thought it wise to unmask Flynn. Why didn’t one get it and pass it on? Biden did his only days before the end of his term. He wasn’t going to have any role, and given his mental abilities even then, what was he going to do with the transcript?
The only explanation is they couldn’t share the unmasked information with each other, so maybe they got the word passed to unmask individually and comment. Biden was the last to get the word.