It's probably mostly a theoretical risk. On the other hand, I recall a flight to Mir that ended up slamming into the station. And NASA doesn't have any reason to accept a risk that doesn't benefit its operations.
Goodwill in the space community and helping to defray costs of future launches by making commercial launches more successful (and thus less expensive, if only for insurance purposes) seem like things that benefit their operations. Perhaps this is a naive opinion, though.
Purely on the basis that the new trajectory can't be gone over with a pin, even if all the maths comes out saying that everything is lovely, you do not refire an ISS delivery rocket that is not where you expected it to be, especially one that has already sustained damage, just to test a new robot.