In the interview he says that he has been invited back to the show since he left and he briefly mentions that still "peeks in" to watch Grey's Anatomy because he adores Sandra Oh. You can watch the interview here
Sandra Oh has never commented on the controversy publicly other than leaving a cryptic remark in Marie Claire, but when asked in an interview if she was sad to see Isaiah Washington go, she said this:
Sandra Oh: How do I say this? For me, it’s been very difficult because I found our storyline very rich. I found it a complicated relationship and I'm sad to see that relationship storyline to have gone. It’s sad.
Would you have liked to see Preston Burke back on Grey's Anatomy to stir things up?