Actually NOPE. He wouldn't be.
The South left the Nation. The South became it's own country, albeit briefly. Ergo - he was a foreign entity and was considered a belligerent. It was just a war. Not an insurrection.
Insurrection is armed rebellion - rebellion comes from within. The moment the south declared their independence from the Union, they were no longer insiders.
Also - wasn't just "set free" like you claimed.
"He bid farewell to the United States Senate on January 21, 1861. A month later, he became president of the Confederacy. Captured by Union troops in 1865, Davis was indicted for treason and imprisoned for two years. He died in New Orleans in 1889."
Notice how he was INDICTED FOR TREASON. He then spent two years in prison. The reason he couldn't take office ever again is because he was TRIED IN A COURT OF LAW and found GUILTY of TREASON.
Trump has not been indicted of anything. Nor did he participate in Insurrection.