I've discussed this with Anna and we decided to overrule the outcome and accept this. The warning shouldn't have been placed given that it is obviously a misunderstanding. The Flash's gang members said he was involved in the raid so he thought he actually was.
There's no way for the player to know that he was involved or not, and if anything this is partially flash's mistake as well as he failed to say he didn't participate even though he clearly could have.