Trump's settlement of $10B lawsuit

How in the world can we justify, as a country, our own President suing the government that he's leading for $10B for a contractor leaking his tax returns, and come away with it with the guarantee that the IRS cannot audit neither his, nor his relatives tax returns?

How is this legal? It's certainly not moral. If your tax return gets leaked, that has zero bearing on the merits of any audit of your tax return that was already in progress. There were no audits initiated as a result of the leak of the tax returns, so how can that possibly be part of a settlement?

Additionally, if everything is on the up-and-up, why would there be any need to shield himself from the audits already in progress unless there was something shady in them? This makes it look like he's trying to make sure he can't be held accountable for tax fraud once he leaves office. Regardless of whether you like or dislike Trump, nobody is supposed to be above the law. I don't know how this can be construed as anything other than putting one man above the law.