I dunno, I think it's an interesting policy. SBR, as they stated, is still going to have accounts, they just don't want individual employees to do so. I can see how a staffer may tend to bias (especially in a dispute) if they have funds in an account and are worried about negative publicity and the subsequent rush on withdrawals. I mean, how many people with money at Royal were wishing the bad press lately would go away for the sake of their account holdings?
All in all, it's probably the appearance of impropriety that SBR wishes to avoid rather than a real conflict of interest. From all that I have heard and read of them, they sound like the most reputable in the biz.