Good thing that you don't actually need to be particularly pro-open to see that they have a point. No closed software can be considered secure, ever; no steps to assure more security "regardless of promises or even intent" can change that.
"Even if this looks like a good thing, this can't be a good thing because it's proprietary". How can you disagree? They bother making the statement, because it's their mission, and to warn off non tech-savvy people who might fall for it.