which means that they could avoid any professional standards issues around knowledge of his guilt.
"Professional standards" are voluntary controls. You can voluntarily ignore them, if the case is big enough. Imagine a case so big, so important, and so profitable that winning it means you become the richest and most famous lawyer in the world. Professional conduct and standards can go right out the window, because you never need to work again. You can get disbarred with no consequence, because you don't need to work ever again.
What kind of case could possibly be that big, important, and profitable? Maybe defending a US President who also claims to be a billionaire? Even if a lawyer commits not only professional misconduct but also literal felonies, who cares? He's the F'in president, he can just pardon you as long as you keep him happy.
I'm not very impressed with "professional standards of conduct" as our only guardrail when it comes to high profile cases. I learned long ago that the key to winning anything in life is learning which rules can be bent, and which can be broken. Ask the Patriots or the Yankees. Ask any NASCAR team. Ask the Kennedy's or the Trumps. Ask any Olympian. Ask any lawyer.