They were already out to get Flynn even before Trump. He reformed Defense intelligence so field commanders could have real time intelligence unfiltered and undelayed by all the self-important Vindmand Deepstaters back in DC. And we have seen what kinds of vengeful Karens [look it up] these Vindman's are when they aren't consulted - they like think it's an impeachable offense if the President isn't relying on their "expertise"
That Trump as relying on well-known anti-deepsters like the great General meant that he had to go. Had to! Our precious agencies in DC need to be able to do their work.