My interpretation of this rule is that you shouldn't promote for instance Stake in Primedice's thread, but it's okay to mention them elsewhere. I'd say this falls under "thread hijacking", and indeed shouldn't be allowed.
I second this. I also think that the key part of the rule is <<
in others threads' >> (and I won't care it it's correctly written or not).
Shouldn't we define what's an advertisement?
I think that you may be overthinking it. Best would be that whoever reported or removed your post. I'd say that somebody may have find your post somewhat off-topic and the link was not a big deal.
Just since it was "in the past", it may become difficult. So I'd say: go on as usual and when a post of yours gets deleted, ask again; you may get better answer than the current guessing.