I’d go a step further, and cause a row again—there is a line of thinking that says Sec. Stanton (with his pinkerton’s and devious intel people) organized Lincoln’s death (recall that Seward was targeted as well- both men stood in the way of Stanton and the Radicals). The Radicals enabled the oligarchs desire, in seeking punishing revenge on the South along with their rather notable seizure of personal property without right of title. Gen. Benjamin Butler comes to mind among others. Lincoln’s ideas was to unite the South back into the Union— nothing of the sort of Reconstruction which Stanton enabled, and resistance to which President Andrew Johnson was impeached and almost convicted (Johnson being a Southerner). Deo Vindice.
The suspicion of Stanton goes right back to the day of Lincoln’s assassination as I recall.
Your other points are interesting as well. Lincoln wasn’t one of the Radical Republicans and they could well have decided he was in their way.
Thaddeus Stevens for one had been accused of having killed a pregnant black woman in Gettysburg around 1830- what would yet another murder be? Especially one that pushed him closer to the reins of power.