sadly, I don't trust a lot of the EFF luminaries and staff
I have always had the impression that (possibly due to shared personal politics?) the culture at the EFF is one that leans away from cryptocurrency
Tornado Cash is essentially a clone of Zcash's technology on top of Ethereum. Zcash has transparent addresses including Bitcoin style transactions between those, so privacy with Zcash just as optional as it is with Tornado Cash. I don't think there's anything different legally.
It's feasible that privacy being the default could make it more defensible but in practice I don't see that mattering. They're just going to declare a private-by-default coin illegal in the same way they'll declare opt-in privacy illegal. Don't think there's a real distinction.