Wear Anything

You're partly right, but the script does allow you to place a block or item in the head slot. To display blocks or items, you need to use Action & Stuff, but you can also use other resource packs that change how blocks or items appear when worn on the head (if any are available). The fact that it doesn’t display without A&S is partly my fault, but it was also developed with A&S in mind and partly for it.