I'm not big on birds on my head, whatever size, but it's my personal feeling. I like having them where I can see them and it's hard to snuggle or kiss something when it's sitting on top of your head. I'm also not too big on bird poop in the hair....course, I have it everywhere else on me, but I don't care for the hair.
All I will suggest is see how the behavior is when allowed on top of the head. If the lovie will not step up and come off your head without being pulled off, I'd say no sitting on the head privileges until that's learned. the same goes for my little turkeys that won't come off my shoulder without being pried off.