As of release #90, LiveJournal has rolled out a new spoiler warning tag.
As such, this mark-up is not appropriate for using as a trigger warning unless you also include some other text that indicates that your post or comment contains possible triggers.
Happily, we haven't noticed anyone using this particular code yet, so as far as we know there haven't been any problems. We'd also like to take this opportunity to remind people that trigger/content warnings are awesome, especially if you state the possible triggers in the same place - and standard lj-cuts still work as normal. :-)
If you'd like to discuss this further, please feel free to head on over to the CVP post, where comments are open.
for the VP Team