I took a look at the map, and as a bit of trivia, Syria to St.P is no longer the longest convoy, it's now Sevastopol to Finland, which is only achievable with a fleet in the Black sea, the Aegean, Tyrrhenian, Mid-Atlantic, Nth Sea and the Baltic. This is because the black sea and aegean are now technically adjacent, along with the Nth Sea and Baltic, due to the double movement.
This is linked to your question in a way; think that the territories that are normally two moves away are now actually touching borders. Whilst it's geographically impossible, that's how it's coded, and that's how the rules work. Whilst geographically you can't convoy over land, the black sea is technically touching the aegean, so in octopus you can.
Just remember, whenever you're confused with this variant, just think; "How would this be resolved if the territories were actually adjacent?"