I would never allow that
Personally the
@Thomasss is right about one thing, that it's a turn off to other users whether they will join your site or not. That's mainly the reason I wouldn't. If you can afford a $1 Dot Com from 1and1.com then there's no need to get a dot.tk domain. It's mainly for young teenagers or children to explore free domains when they are young and don't have the money. At least that's what I did when I was a kid.
@NewsProject look for the archive of this site from 2003 (Yahpoolerz.tk). It was my site from 2003. It wasn't up long but I guarantee it was within that year. I want to see what's on it. I would be excited to see what it looked like. That was when I was 13. If you find it, I will post those 10 posts on your site by the end of the day instead of in 4-5 days guaranteed. Post the link in this thread.