It says that the grilled eel over rice dined and dashed. It sounds like a euphemism to me. It is not very different from saying the grilled eel over rice developed legs and ran away. In either case, you are suggesting someone stole it.
As a Japanese person, I can confidently say that うな重が食い逃げした sounds nonsensical to Japanese ears. The verb 食い逃げ means the subject (うな重 in this case) ate something, not the other way around. Regarding euphemism, you could instead use expressions like うな重が消えた ("うな重 vanished") or うな重が旅立った ("うな重 set off on a journey") to metaphorically describe someone eating their meal.
But... come to think of it, even a native speaker may not be in a position to deny someone's finding about interesting similarities between Japanese and English sentences and possibilities of interpretation.
I just realized the example might have had a typo like you said. It is an interesting typo since it reminded me of a similarly absurd expression in English. When the expression is used in English, the entire point is to be nonsensical such that the only resolution is that someone moved/stole something.
As I am still learning, I have been trying to be open minded about possibilities. That helps when encountering things like 風邪です and 空気がおいしい. The former as you know literally means wind, but also can mean having a cold (and it would be very socially awkward if someone’s name was 風邪). The latter literally calls the air tasty, but means the air is fresh. The downside of being open minded is that someone can tell me something wrong and I will try to interpret it under the assumption that it is correct.
That's interesting, because I took the sentence verbatim from a linguistics book (辞書には書かれていないことばの話、仁田義雄). It says うな重 is short for 「うな重を食べた人」. It was compared with 漱石を読んだ (-> 漱石の作品) and 及第点に荷物を持たせよう (-> 及第点を取った人)
So you're saying that this sentence makes no sense unless は is used?
