it only means his Chinese skill is too low and that he can match native speakers only in everyday speech, not literary speech. Matching native speakers in everyday speech, even highly technical, only means that they are maybe middle school level.
Imagine if Putin wrote something like the below to Boris Johnson Liz Truss Rishi Sunak, as an example using western languages:
"I understand that you must navigate the Charybdis and Scylla of Ukraine with regards to domestic political constraints and the prospect of catastrophic escalation, but I warn that should you open Pandora's Box with further provocations, the fate of Sodom and Gomorrah may befall you. Retreat from the banks of the River Styx while you still can, or risk being swallowed by Cerberus."
If someone said that was "too hard" or "too opaque" to understand in English, that's their problem, not the writer's. Just because 90% of English speakers can't write like that, doesn't mean that it's bad writing.