Trump still gets protection on tax immunity:

[Prairie Gates]

4. There really is no mechanism for any administrative "immunity" to survive the administration

A judge can dismiss specific charges with prejudice, or Congress can pass a law related to a type of enforcement. But an "agreement" or supposed "rulemaking" between Justice and IRS about whom can be audited lasts exactly as long as an executive order: until the next administration decides it is inoperative.

Point being, this is face-saving in the extreme. Trump was told absolutely not on the slush fund, which was the real prize, because it is in fact a shadow legal defense fund for the massive corruption investigations that are coming for the Trump family. The "immunity" was always a relatively meaningless added perk, since it can be rescinded as arbitrarily as it was granted. Now it is just a way to soothe Trump's bruised ego about not getting to keep the $2 billion.