Len, I've read a few letters and diary entries from members of the 3rd Arkansas about the winter that Taliaferro's brigade spent literally left out in the cold. My memory could be off, but weren't they near Bath, Virginia? Anyway, I've read poignant accounts of 3rd Arkansas picket guards being found frozen to death at their posts; and I presume that the other regiments of Taliaferro's Brigade had similar tales.
I've also read that Jackson had a strong, personal dislike of Colonel Rust. Albert Rust was a typical Southern politician--a somewhat pompous, loud, name-dropping glad-hander; but he was also a well-educated man, totally devoted to the welfare of the men under his command, and an early and dedicated supporter of the Cause. He wasn't the world's greatest combat leader, but he was highly regarded by his officers and men, and they would follow him anywhere.
But with Jackson, first impressions were the ones that counted, and he tended to see things (and people) in stark black and white -- all good or no good. To him, Rust was an amateurish buffoon, and a lax disciplinarian who tolerated un-military and un-Christian behavior in his command.
The parting of the ways of Jackson and the 3rd Arkansas was probably seen as "win-win" by both parties.