When I soaked my Dawes a few years ago, I drilled out the old rivets and reattached the head badge after with some correctly-sized drive pins from McMaster-Carr. I think the pins were a few cents each, plus 8 bucks for shipping, or something like that. It's a nice neat job, and really looks original, though someone who knows what original is supposed to look like on that bike could easily tell that it's not.
I was hoping others had tried the "coat the badge with grease" trick, and could tell me for sure that it works. How could it not? Yes, better safe than sorry and all, but I really dislike removing and remounting head badges. If I do feel brave (or foolish) enough to give it a try, I'll report back on whether it works.
JV