Thanks for your concern. As you noted people can use og tags to customize their share previews on Facebook. This is especially useful for people who use third-party systems for analytics and tracking, where the URLs people click on may redirect to the actual article. This behavior allows the share preview to reflect the actual article contents rather than the interstitial page in the middle.

Now, lets imagine we took this functionality away. How would malicious individuals adapt? They would still retain the ability to engage in standard cloaking techniques, like sending our crawler to one destination while sending real users to another. We have automated systems in place to detect such attacks but by their nature they are imperfect.

So taking this behavior away would disproportionately affect good publishers without much hindering malicious individuals. It might also push good publishers into more malicious behavior to try and restore the behavior people expect. And it would result in an overall poorer end-user experience. Given all of that we do not plan to make any changes here.

Although this issue does not qualify as a part of our bounty program we appreciate your report. We will follow up with you on any security bugs or with any further questions we may have.