And for that reason if they are really concerned about the whole do-not-overclock-or-your-warranty-is-void issue, they should share at least some facts from that data. Like it was said - we are grownups and some of us are techy enough to understand these facts.
When you want a kid not to do something, you don't just go and say "Don't do that", you should say "Don't do that, because ...".

And if in this case the only "because" Nokia can bring up is "the warranty is void" - then technically this is not a showstopper, but may pull back some people from doing it (certainly not the ones reading this thread )