On the contrary
Having googlebot follow the in-page TOC links is a good thing, because it naturally weights the popularity of a topic. Google's PageRank algorithm is based on link frequency. The longer a thread, the more in-thread links there are, and so Google automatically recognizes that thread as a hot topic and it shows up higher in the search results.
Which, of course, also means that some of our flame wars will float to the top, as well as those "flush it!" threads which are contrived to fill up space to push a lower thread off the front page. My my, what will Google think of us?