I think everyone agrees that a LIKE operator would be ideal, but that's probably not in scope for an initial 3.4 release.
Still, I'm uncomfortable with the initial approach of overloading = to mean "satisfies index expression." The problem is that it will be very difficult to back out of this behavior once people are using it.
I propose adding a new operator in the interim instead. Call it MATCHES, maybe. With the exact same behavior that SASI currently exposes, just with a separate operator rather than being rolled into =.