Plus, I feel it's worth mentioning that this is only based on our current understanding, situation, and technology at our dispose. Bitcoin, could eventually be broken, the very algorithms that it relies on could potentially be broken in years to come. What we base our assumptions on or our determinations if you will is it's currently impossible. That doesn't mean it will forever be impossible. Obviously, this means that a whole lot of our current technology outside of Bitcoin would also be compromised. It's not a major concern right now, but it could potentially be a problem years, and years from now. Potentially talking decades or centuries.

So, yeah proof of burn addresses are good enough for the conceivable future to determine that they aren't recoverable.