"with no evidence" -- Actually, this is one ruling in which JudgeB ruled fairly and got it right. And, while it would be nice for KR to have the legal mind of Bederow on staff, adding him to the team created potential pitfalls for both KR and TB. (Bederow is TB's attorney IIUC.) JudgeB's ruling avoided them.
BTW - KR couldn't get Bederow's help in an informal way, because unless she has actually hired him, there is NO attorney-client protection for what he might learn. You don't want to open that door where he's being put on the stand in some Brennan fishing expedition for information.
Anyhow - The conflict of interest was factual! It stemmed from the reality that the cw had charges looming against both KR and TB. Their actions intersected. It's possible that one or the other might need to say 'They did that, and I wasn't involved at all' for something or another.
AT THE SAME TIME, the cw wanted to link KR and TB together, claiming they had coordinated illegal actions (supposed witness intimidation by TB at the request of KR). JudgeB wouldn't let them have the same attorney, saying each needed their own independent attorney in dealing with the nuances of such charges - who did what, why, who knew, etc. Each being able to work for their own best interest would be vital when one or the other was on trial for such actions. That was 100% the right ruling.
That separation of attorneys worked liked it was supposed to, in fact (and in a way that the cw didn't like when it got there). Early in the KR case pre T2, the cw tried bring TB into the KR case, to force testimony/evidence from TB that supposedly was relevant to the KR trial. It was a classic Brennan fishing expedition on the flimsiest of pretenses and probable falsehoods, as always, but it was quashed legally because, with TB and KR fully separate and independent, TB's team asserted that the cw was just trying to use the occasion to violate TB's rights to refuse to testify against himself re his own case. Not having the same attorney made that separation very obvious and JudgeB had to rule for TB (which also helped KR, because it shut the door on that fishing expedition where Brennan had hoped to create side issues to later make KR look bad to the jury).