The nuts can be removed from the pins and the emblem taken out without destroying it, generally you sacrifice the nut. A small dental pick and mini screwdriver make this easy work.
You could use 3M tape in the grille to tighten things up and keep future rattles at bay.
You and me both... The one I ordered had ONE pin... and 2 loose in the bag, making one missing... straight from a retailer. So that's wasted money, especially since I used a mail forwarder to get it over here... so they'll probably just blaming each other and the USPS over whose fault this is...
(It came in a plastic bag in a tiny envelope - soooo surprised they snapped!)
How can you get 3M tape to make it stick when there's almost no contact between points between the pony and the grille?
You can build up 3M tape relatively reliably or I would suggest using a permanent filler such as 2 part epoxy to fill the void and make a level surface to apply the tape too.
JB weld may work, but for 3M attachment I prefer the epoxy that comes in the syringes, it leaves a less porous surface much like plastic. Just mix, squeeze in, and let it self level.
I did this on the back of some 1968 Tribar replica emblems after removing the pins.
This also makes you appreciate the classic emblems that are made of metal.