I believe that too. However, I think that a topic starter has responsibility for what happens inside his topic. At least, this is what I think about my topics. As the situation is now, the following questions pop in a natural manner: did btcltcdigger know that his topic will be used for bumping services?; if so, was he paid too, to allow the spam?; why didn't he do anything to defend his reputation (e.g.: clean the topic or state somewhere that he is not involved anyhow in that spam nor he was paid for initiating a topic for pure spam)?
That would be difficult to confirm. It doesn't seem like all of his threads are using bumping services. So, there's a lack of data to make any sort of accurate conclusion. Also, can't comment on defending their reputation, doesn't seem they're active in the reputation section. I've taken a look at a few of their other topics, though. They don't seem particularly concerning.
It might just be that they post it, and then don't monitor it much afterward, which definitely wouldn't be the way I go about it, but I guess some users do that.