*edit: Seems YC participated in the follow-on round after the batch ended, so I imagine some extra due diligence goes into that.
This applies to investors at any company. At some point you have decided to believe in the founders and executive team, rather than deal with daily operations and micromanaging your portfolio
* all the laws are to protect investors from issuers
* splash around money to incentivise securities fraud
* buy a pile of tokens
* if the SEC doesn't bust the issuer, the VC wins big
* if the SEC does bust the issuer, the VC gets their money back and doesn't lose
it also realises liquidity much quicker than the long and tedious process of backing a tech company that does things
So did YC buy the tokens, or buy equity in the company? If the latter, then they're part-owners and may claim to have been completely hands-off, but might need to show it.