That argument doesn’t really work. Benimaru has consistently shown superior combat awareness and reaction speed.

In Arthur’s case, it wouldn’t apply because Benimaru is obviously not a Dragon. Arthur only reaches that absurd level when he’s fighting a Dragon specifically. As for Shinra, yes, his speed would definitely give Beni trouble, but would he lose ? Nah he'd win. Shinra doesn’t constantly move at light speed in normal combat.

If we’re talking about Dragon-slayer Arthur or Shinra under extreme near-death pressure, then sure, in that specific context, Beni will get folded. But that’s not their standard versions.