@dcent I'm afraid it is not that simple.
For every request from a search engine (already questionable), there are tons of other requests pretending to be search engines. I try my best, even with the contents in here being public, to stop automatic profiling of the accounts.
So, sorry, but no, I can't change robots.txt settings.
If you want to increase the visibility of your posts, I suggest linking them from other sources (webs, other social media, promoting your account in person, etc).