Yeah, the Oversight Committee probably got turned into a rubber stamp for Clark's policies, staffed by Senators like the current one we meet in "And Now For a Word," Quantrell.
Plus, Sinclair was a lowly commander, with little evidence that he'd ever had so big of an assignment. He may well have gotten into the habit of checking in fairly regularly. Whereas Sheridan was used to high-profile positions, as he's mostly been in them since the war. Commanding the Agamemnon he learned how to operate independently. He's got lots of confidence. Plus, people probably have more confidence in Sheridan than they did in Sinclair. Sinclair was pressed on them by the Minbari, was a bit suspect, and has never held such a huge command. Sheridan's been highly respected ever since he took out the Black Star.
So combine a more confident and more trusted commander with a weaker senate committee, and that particular background element simply becomes a waste of space.