Plagiarizing entire passage of text without proper attribution is completely irresponsible and unacceptable. The least you can do is provide a link to the original.
The first offenses of blatant plagiarism without attribution will merit a warning and deletion of the answer. Subsequent offenses, depending on the frequency and severity may result in possible suspension of the offending account, on top of deletion of the answer. For unregistered users, simple deletion of the answer is enough.
With that being said, even if the original writer, David Sodeyama, is in the right. Soliciting votes and views on another Q&A site within an answer is discouraged. These answers should be deleted, because they are not answers. We are us and they are they, it's fine to cite a passage from their answer on another site, provided you properly attribute it. But don't go about asking users to go to another site, register, and vote on your answer.
Subject to these Terms, Quora gives you a worldwide, royalty-free, non-assignable and non-exclusive license to re-post any of the Content on Quora anywhere on the rest of the web provided that the Content was added to the Service after April 22, 2010, and provided that the user who created the content has not explicitly marked the content as not for reproduction, and provided that you: (a) do not modify the Content; (b) attribute Quora with a human and machine-followable link (an A tag) linking back to the page displaying the original source of the content on quora.com; (c) upon request, either by Quora or a user, remove the user's name from Content which the user has subsequently made anonymous; (d) upon request, either by Quora or by a user who contributed to the Content, make a reasonable effort to update a particular piece of Content to the latest version on quora.com; and (e) upon request, either by Quora or by a user who contributed to the Content, make a reasonable attempt to delete Content that has been deleted on quora.com.
All in all, it's been made clear that the user in question did not personally write the answer. It should be noted that subsequent plagiarism attempts in the future by this (currently unregistered) user will result in the destruction of his user account, without any further warnings.