I think the point of ethics regimes and things like blind trusts and ethics screens is that we can enable the participation of people who are elected to public office and want to serve. It's not to prevent participation or create obstacles to participation. It's about enabling the participation. If we need to create those kinds of regimes so that we know the public interest is being protected from any potential private interests the person has, that's completely appropriate.
We also do not live in some kind of parallel universe where, when someone becomes a public office holder, they stop becoming a private person. That isn't true. We're not living in some kind of made-up, fairy-tale, perfect world. We have to find ways of managing the person's private interests while they have these public responsibilities, and blind trusts are a way of doing that.
We don't know when someone enters into a blind trust. The person might have sold all their stocks and you had no idea. That's just the uncertainty you have.