The older I get, the more I'm convinced he's right. The names of parts helps give some amount of context and purpose to why a thing was done, what it's role is, etc.
This gives a much quicker comprehension to the thing you're trying to understand - consider someone handing you a codebase you've never seen, and a vague description of what it does. Is it easier to understand with well named functions, variables and types? What if the all function names were replaced with f1, f2, ... fn, and variable names were replaced with v1, v2, ... vn, and so on?
What if it wasn't a complete codebase, but only part of it, and had gone through a bit of a scramble (the Carthaginian ship in question had been wrecked as I understand it)? What if you were a brand new programmer (Rome was new to the whole ship thing then...)?
You're absolutely right that it's not strictly necessary to have the labels for reverse engineering, but the labels certainly help... for context it was 8 years from the start of the war until the battle in question, and the fleet was built in just 4 years. At that rate, I find the label thing a plausible contributing factor.
The principal cause for why Rome was so successful at beating up its neighbours was well-executed logistics and a capable bureaucracy.
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[1] Interesting, but non-nonsensical. How would labeling the parts of an already-completed ship meaningfully impact reverse-engineering efforts? It's a ancient ship, not an composite airplane, or a microchip, you can rip it apart, piece-by-piece, without the benefit of labeling.