Hi YM:
The question is, if blocked, where will those "searches for minor topics" go? If not to AYP, then it would be a net loss of traffic.
Correct, there is no robots.txt file on aypsite.org . We do have one blocking the entire aypsite.com site from the search engines, because mirror sites are not permitted by Google, and both would be blocked by them if one was not blocked by us. Years ago, aypsite.org was chosen as the search site, because it includes both the lessons and the forums, whereas aypsite.com is the lessons only. As mentioned before, aypsite.org (including the forum) is site mapped for improved search engine exposure.
The thing with doing search engine access modifications is that no one knows what the Google algorithms are, and there is risk in it. We could end up shooting ourselves in the foot for the sake of a few errant search results, which have links to the corresponding topics anyway. Very often, "upgrades" result in unexpected downsides due to unknown factors in the technology.
So from the perspective of a long time, well-established search engine exposure program, this is a case of, "If it ain't broke, don't fix it." At least not for now...
Thanks for poking around. We are always looking for ways to improve the AYP resources and their visibility. But at this stage we are not inclined to do modifications that offer a small benefit coupled with a potentially big downside risk.
The guru is in you.