I think that trust is burned already. I moved away from Proton to a German provider that sponsors its own infrastructure to be developed as FOSS (yes that means they are commoditizing their own product, but it is the SERVICE that's paid for).

Having shareholders means that the company WILL NOT continue to serve their customers. Any company that has external shareholders is untrustworthy. Everybody should consider them as disposable. It doesn't mean that you cannot have a deal with them, now but the parties should be aware that anything that you share will be misused. So if Proton has any external shareholders, it is already untrustworthy to me.

Therefore, they cannot really gain any trust by being activist shareholders and change leadership. They already supported a certain "persona" to make them money.