It is because a phrase with a lot of periods in between is considered a word, and a “too long” word. This has come up a few times @eviltrout and that regex should be changed to consider a period a “space” for the purposes of that check.
The goal is to block topics that have a title of aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa but the check needs to be a bit smarter about what it considers to be word breaks.