Which is fine tbh. I don't think everyone should scale to the feat calc'd for David since that's like David near his peak with enhancements and a military grade sandevistan to boot. Reflexes and other implants evidently also contribute to speed, and thus only high-tiers which David should be considered should scale ONLY with a Sandevistan. Low-Tiers or Mid-Tiers should scale off their own feats.
Supplementary evidence, a secondary evidence. It isn't at any point used as a main piece of evidence. It's like "Hey, on top of all these feats, there's also this drink that's a direct reference to the thing that is consistent with the actual thing". It's not "This scan means Sandevistan is uncontestably a nanosecond reaction timer enhancement".
I haven't calc'd em yet, but I already said above there's several other feats that look Sub-Rel to Relativistic above. Such as feats involving the railgun which I can likely see getting Massively Hypersonic off of dodging it alone, possibly getting higher with military grade sandevistan. There's two other bullet freezing feats in the Anime, and even something like David seeing blood falling at near statue speeds could give sub-rel results.
But again, at no point would it be a main argument, just a minor piece of text that is made in reference to the real deal.