Just saw the Jinbe, Arlong panel & the phrase is indeed used to hype up Arlong’s strength in comparison to Jinbe’s
Problem imo is not the phrase itself. In my opinion It’s a bit daft to debate whether the phrase means what it means because of one panel. The phrase is the phrase. Problem however is the reality of how Arlong compares to Jinbe atm.
One explanation for it is that Oda retconned Jinbe’s power level hence the discrepancy. In the first place, someone as weak as Arlong being a commander even in a veteran level crew at this point in the story makes no sense much less along side someone like Jinbe but we gotta keep in mind that the PLs of pre-ts villains have inflated as we’ve gotten deeper into the story with Croc being the perfect example of this.
Unfortunately we never really got to see what Jinbe was capable of prior to his comparison with Arlong so there was not really a bench mark which is the problem. Isn’t really the case for Gaban in comparison to Ray & Roger though.
Also, to be exact, the line about Arlong & Jinbe was ‘He’s a fishman pirate that once upon a time stood shoulder to shoulder with Jinbe, one of the warlords of the sea’. There’s a qualifier, ‘once upon a time’ which was more than a decade ago maybe even two. Need to verify with Koala’s age, so it could also be the case that Arlong was comparable to Jinbe during their voyage on fisher tiger’s crew. I mean we’ve got comparisons btw Kaido & Moria several decades ago but Moria wouldn’t even be able to tie Kaido’s show laces atm.