On an entire kettle, the only place you want to punch a hole is at the seam? Have you ever seen anything on the seam before in any pics posted anywhere?
You can punch through a seam, but it puts a lot of stress on the metal when punching. If you punch it, and then crack the seam, where will you be then?
I say it's safer to stay away, but go for it! Kettles aren't cheap...