Let's start small and work our way up.
Is consensual sex "bodily harm"? No.
Is nonconsensual sex (rape) "bodily harm"? While there are hypothetical situations where it isn't, I'm going to summarily say "yes" anyway (Yeah, I'm waaay out there on a limb, I know.)
It follows that a threat of rape is summarily a "threat of bodily harm".
And now of course we get to "credible".
It is my experience that there are about a million threats of bodily harm on the Internet to every actual case of bodily harm. Maybe even more. So I'm going to go out on another limb and say that most threats are not credible.
In fact I will go so far out as to say that my null hypothesis is that a threat is not credible.
In other words, I need to be convinced that a threat is credible before I impose a sanction.
This convincing can come from evidence provided by the target of the threat, or it can come from my own investigation.
If I see that both the threatener and the target have IP addresses in the same city, for instance, that's a big step towards credibility.
But I am not going to do more than a cursory investigation, because like I said the chance that it's actually credible is about a million to one, and I have a couple other things to do.
I will be open to other evidence provided to me, of course.
Of the "actionable/not actionable" section, the key line is "Abusive language directed at another user."
This time, the sticking word is "abusive".
Sometimes the relationship between two people is obvious to me. If Karyn said "TheLostVertex, I'm going to give you a roofie/viagra cocktail and ride you till Springer comes on," I would not consider that abusive because I know that they are good friends and that she'd be joking.
However, if someone quoted Mike Tyson's infamous line "I'm going to rape you till you love me," well, that's a whole different story, especially if there's a heated argument going on at the time.
But all they'd probably get is a warning.
I'm in a lose/lose situation here. If I ban someone for a single, non-credible, rape threat, then half of the members here will come after me with pitchforks saying "Really, Beleth? You took that seriously? You're incompetent." But if I give someone a warning, it'll look like I've done nothing (because I don't discuss warnings with third parties (and that behavior is non-negotiable)), so the other half of the members here will come after me with pitchforks saying "Really, Beleth? You let that slide? You're incompetent."