Defense attorneys aren't weasels as a group. They're a necessary cog in the justice system.
Think about it: why are his clients getting off? Is it because the cases against those clients weren't strong? Because people were actually innocent? Because the police or crime labs didn't do their jobs properly? Because the prosecutors aren't holding people accountable? And, if somebody got off despite being on probation, that's doubly true, as PVs are generally at a lower standard (preponderance vs. beyond reasonable doubt).
Our society *needs* great defense attorneys. Yes, usually their clients are guilty, and often they'll re-offend. But, if the police, labs and prosecutors did their jobs, there would probably be a conviction. Our government needs to be accountable not to cut corners. And, in the case of the falsely accused, somebody needs to be there to defend them.
There are thousands of people who have been falsely convicted. I can't imagine how much worse that would be if there weren't defense attorneys fighting for them. If the system had even an iota of prosecutorial discretion, maybe the need would be less. But, there have been way too many examples of prosecutors charging people just because they could, rather than because that's where the evidence undoubtedly pointed. From experience, they tend not to care if the defendant is able to make bail, or about how much attorneys fees are costing them, or how many people they're harming. If they can charge, they often do, regardless of the probability of actual innocence. Hell, I've seen prosecutors who absolutely knew somebody was legally innocent who have said "let the jury decide". Pontius Pilate shouldn't be a role model.
I mean, if you're genuinely curious about his perspective, ask him. But, if you just want to be confrontational, I'd keep the opinion to yourself. It serves no purpose, and honestly, you might be in the wrong regarding the ethics of this.