I argue in my white paper that TaPoS is as objective as proof-of-work.
Okay, but does it also provide objective consensus in the strict sense of the following definition (personally, I'm sharing Vitalik's opinion that weak subjectivity is sufficient)?
A consensus protocol is objective if a new node can independently arrive to the
same current state as the rest of the network based solely on protocol rules (e.g., a definition of the
genesis block) and messages propagated across the system (e.g., a set of all blocks).
By that definition, proof-of-work is also not objective, because you don't know which hidden chains are the longest chain. You are trusting that the sources who send you chains are omniscient.
Vitalik's entire premise was undecidable and irrelevant.