Just PM them, you really can't force people to unlock their personal property. If someone was displaying their treasure, then they were done and locked it away from the world, you can't make them open it. Even though that comparison sucked, you should get the idea.
He said he might want to add something onto the advise that was given. But that doesn't mean its just for that person. I mean, if the last advice given was enough to solve it for
them then thats all good and dandy, but if its bad advise, it wouldn't hurt to add some better, more descriptive advice for anybody. Check out my previous comment for a slight elaboration on what I mean. Maybe you don't necessarily want to give that extra advice to just that one person via pm? Maybe you want to add onto there for whoever else visits that topic, or might have the same issues.
No we can't force anybody to do anything, hes just saying it would be nice if they wouldn't lock things without any reason really, other then their problem being solved for
them alone. Because it's kind of nice to leave them open for other peoples benefit.
In the end the main question is, "is it really necessary?" If there is no real reason to lock it then why lock it? Even if you got what you were looking for, leave it open in case anybody else wants to discuss it. After all its a discussion forum.