I stress that auto-deleting my own posts is not something I would, personally, consider doing. I try to live by an old Russian proverb--"Man is master of the word left unspoken; once it is spoken, it is the master of man"--and in general maintain a civil and facultative online persona. Moreover, such a brutal approach would leave traces (e.g., quotes from the deleted posts) that would in turn drive opposition researchers to try to retrieve the original posts through Google caches and the like.
However, I can easily see the self-deletion issue coming up in the future given that our posters have a higher degree of political engagement and a firmer grasp of policy detail (at least in the transportation field) than the general population at large. We live in an age where political careers have come to an end as a result of mismanagement of digital lives (Hillary Clinton's email server; Anthony Weiner's sexting; one of Trump's nominees for a federal judgeship appearing to endorse the Confederacy in a blog post), and this incentivizes aggressive approaches to reputation management even when they are ham-fisted and self-defeating in the long term.
The existence of digital records in itself makes youthful mistakes easier to excavate and as a society we still haven't come to a consensus on when, or under what circumstances, these should be allowed to lapse into obscurity, whether this is through the digital records ceasing to exist, being hidden, or being left in public view with the understanding that they are not to be counted against the person they would otherwise show in a bad light.