Mike Flynn's crime

So, according to the statement of the offense, Mike Flynn's crime is that he told the FBI that he had not asked the Russian ambassador not to retaliate against Obama's sanctions against Russia, when, in fact, he had asked.

Obviously, Flynn should never have lied to the FBI. But, if he did, the whole story would seem to undermine the claim that there was collusion between the Trump team and the Russians rather than support it. For, if there was collusion between the Trump team and the Russians, then, presumably the Trump team gave the Russians something in return for sabotaging Hillary. But, Flynn wasn't giving the Russians anything, but instead was asking them to do the Trump team a favor, namely, not to escalate the situation. And wasn't it good for the US if the Russians didn't escalate the situation? And, in fact, the statement of charge makes clear that the Russians decided not to escalate the situation as a result of the call. And wasn't the making of such a request from a senior official of the incoming Trump team an appropriate part of his duties?

If the lie is all Mueller has, I don't see the big deal.