This lays the groundwork for the next appointee who should study Roberts performance and carefully answer or not answer what's asked. If that person could be as reasoned as he, it would be very difficult for the dems to deny him/her the appointment (that's to say he/she comes with no baggage).
Didn't work with Bork.
"I don't see any other grounds to deny his appointment."
Other than the unspoken grounds that special interest groups will cut off their contributions.