It’s solved for everyone who is always periodically syncing.
Also, if you’re comfortable with Bitcoin’s security model, then for Tendermint you only need to get a trusted block hash (after a long period of being offline) if and only if you detect a fork in the block-chain. Most of the time there won’t be.
You are outsourcing the trust problem, not solving it.
It’s solved for everyone who is always periodically syncing.
Also, if you’re comfortable with Bitcoin’s security model, then for Tendermint you only need to get a trusted block hash (after a long period of being offline) if and only if you detect a fork in the block-chain. Most of the time there won’t be.