Agreed that it will be a trainwreck on this forum, but disagree with the way you're framing it.
Speaking very generally, teraflops do matter between PS5 and XSX because they are targeting the same resolutions and framerates. XSX will either produce a better image at same resolution and framerate as PS5, or the same quality of image at a higher resolution/framerate, or some combination thereof. PS5 designers and owners would probably prefer not to give up an advantage on any of these aspects, but the TF difference is a rough indicator that, usually, they will to some degree. (Whether that difference is large enough to care about is another issue entirely.)
Sounds reasonable and lines up perfectly with PC GPU tests.
I don't think a difference might be seen if a game is well-optimized to a locked framerate though, unless you're Digital Foundry and notice that the magic they did really wasn't magic at all.
But that's a whole other thing. It's the all too common scenario when a game is struggling to maintain a locked framerate that will show the hardware differences the most. That's when pure hardware specs usually matters.
Lockhart will explicitly target 1/4 of the resolution of XSX and PS5. So criticizing its teraflop count will make less sense - it is intentionally producing a lower resolution image in hopes of maintaining similar quality and framerate with fewer teraflops, and will be openly sold as such.
That sounds good in theory but don't really make teraflops matter any less, the target resolution is just lower. It happens on Xbox One today, and Switch, even PS4 Pro. And if the strategy is to simply target 1080p instead of 4K, then what happens on Lockhart when a game comes along that can't quite reach 4K at the targeted framerate on the XSX so they go for a lower resolution?
720p on Lockhart? 20fps? Downgraded visuals?
I just don't think there is any magic that makes hardware limitations disappear, there is only smoke and mirrors and clever compromises.
In the end I understand that the end user might not care anyway depending on why they bought the cheaper console. But that's not why I quoted what Brad said, I just found it interesting that the teraflops count would matter between PS5 and XSX but not between XSX and Lockhart. They might actually matter in exactly the same way, just not on the same degree, all depending on how much the higher spec console is pushed and how clever the dev is when it comes to hiding the required compromises on the lower spec console.
DF will have plenty of work next gen that's for sure! ;)