> Or do you really think that if someone has such concerns, their only recourse is to start contributing to the project?
Yes, I think one way to not come off as entitled when being critical to volunteers is to also offer volunteer work yourself.
And it's most helpful to provide feedback directly to the developers through their preferred means of communication.
> Or do you think they're not valid concerns?
Irrelevant what I think here, that's kind of the point. That's just my opinion.
> That project of course being one of the most security-sensitive projects one could imagine.
Agreed that the project is important. However, this is irrelevant, too, unless you're bolstering your "valid concerns" argument.