Fair enough. Lincoln's assassination certainly unleashed the worst impulses of the radical Republicans. But whatever he might have done had he lived it would have been small consolation for the damage inflicted during his reign on the Constitution and the rule of law.
There are those of us who believe Lincoln saved as much as he could of the Constitution and rule of law from those intent on destroying them.
If you think Lincoln was particularly aggressive or unlawful in how he handled opposition, even treasonous opposition, you might want to research how similar issues have been handled in other great civil wars. The US WBTS had far and away the least oppression and fewest atrocities of all such wars in all history. (Which unfortunately isn’t saying all that much.)