You got to give people time to get back to you before you start frowning my friend. At least for me your question was posted at 1:47 AM so I was fast asleep. Hiding lastmessage is easy via CSS, but you may be better off having someone develop a quick little addon for this if you require certain criteria. Might I ask, why do you want to do that?
If anything I would like it to change to "Be the first to reply!" or something inviting like that which causes the user to act.
Think it would be good to have an addon that if the posts are zero it says be the first to comment or something.
I may take a look at it once I finish my site and see what I can do - unless off course someone who has allot more skill than I do comes up with something before I get the chance.
I don't know if this will help the original poster but think for many of us it would look allot better and be truly useful.