Can’t happen this time because Mitch isn’t running the Senate…
BUT…
Here’s a scenario…
Thomas drops dead.
Sinema or Manchin change party to Republican.
Senate flips to Republican leadership and Mitch is back in charge because he doesn’t step down from the leadership role until the term ends.
Mitch blocks the nominee just like he did with Merrick Garland.
Trump wins and gets a 4th Supreme Court pick… which doesn’t change the balance, since Thomas is right wing, but it locks in the 6-3 majority for decades.