Unless there is proof from evidence like Roman's communications, I don't see how can they prove that he knew in advance that people were going to use Tornado Cash to launder money. While laundering is obviously a risk with any privacy protocol, that doesn't mean that its creation was intended for that.
I (sarcastically) wonder if any bank executives have been under this much scrutiny for laundering, since banks (arguably) have much worse laundering statistics/affiliation with criminal activity are much higher than that of what all of the crypto ecosystem have involvement with.
It wasn't intended for money launder but they've got email evidences saying he's guilty because he didn't stop money laundering after he knew it was happening. He's got to clear his name in court or he'll get years in prison.
If the basis is that he knew ML was happening though didn't stop it, I think it will be argued that it is impossible to pick and choose certain transactions from interacting with a smart contract/decentralized and non-custodial protocol, and a complex job (technically) to identify or add any kind of measure to prevent it (any faster than how fast they sanctioned Tornado Cash to begin with). That's only what I think though, I'm interested to see what will be ruled.