All this appears to be a very far-fetched scenario and would very noticeable as the transaction volume spikes up.
Would you notice right now, if for example there was 1 real transaction per block (as probably is likely given the close-to-zero adoption of Monero) and 4 Sybil transactions?
The scenario basically is that the government takes over Monero mining, doing massive number of fake transactions and big data analytics and it's game over. That goes for every crypto right.
They can purchase the data needed when they need it. Someone else can do the mining and Sybil transactions for profit. Analytics could be done for every crypto (except for Zcash) yes, but it would be especially attractive to do that on a crypto where its users think they are anonymous.
Is it me or is the recent news of WannaCry where every researcher and blockchain analyst said Monero is completely anonymous, it's blockchain is opaque and we can't trace anything resulted in a strategy from FBI, NSA coming up with a strategy to FUD on Monero so it doesn't gain adoption?
If you had a honeypot, would you say it was or wasn't?