There are obvious and ample reasons
to do so...
Both audits were conducted under the leadership of Trump’s handpicked IRS head Charles Rettig, who remains IRS commissioner to this day after President Biden chose not to rock the boat last year by replacing him. As with other Trump appointees left in power, from disastrous USPS Postmaster General Louis DeJoy to Federal Reserve Chair Jerome Powell, who is currently trying to “get wages down,” the fallout proves that continuity is not the same as stability—especially after Trump’s presidency.
I have no understanding of how replacing him is "rocking the boat."