TL;DR: Maybe a bit harsh, but get rid of him/her.
Most companies have a defined culture or core values. Suggested is to use your core values in the hiring process. I think the same goes for the firing process, fire to protect your core values.
Introducing Agile is a team culture shift according to the Agile Fluency Model. People blocking this culture shift should eventually be removed. I would discuss this with the person for a max period of 4-6 months. Discuss this aswell with upper-management and announce that not changing the culture is not an option. Make sure that it is clear what is expected from this person. Keeping people around with the wrong attitude is not worthwhile for both parties. This person will be happier in another company probably.
If it is a larger company, maybe some more traditional teams exists. I would suggest to move this person there.
Culture is important:
Value your culture and values highly. Showing that the company makes exceptions is the same as saying: "We do not take our values seriously". Now everyone will just do whatever they want. This is not the path a company wants to walk.
Continuing to tolerate this behavior will demonstrate to the rest of your company that core values are optional, and not truly core to building your company. This would be analogous to a cancer in your body that you have chosen to not remove.
http://www.rhythmsystems.com/blog/bid/87071/fire-to-protect-your-core-values
Waste of time:
Some people are open to change, some would rather just see how it works out, but some just push back. My experience with the last group is that is just a waste of time to convince them. They will keep making stupid remarks about the process and Agile principles or ideas. Agile has proven itself over time now. I have no need for people pushing back in my teams.