Just as an experiment, mind.
What happens if you copy them into:
Root/Library/Application Support/Adobe/Fonts
I'm curious about one thing though... some fonts have permission settings (the permission bit) and I'm wondering if that somehow maybe involved.
As an example, I recently downloaded a free but Macromedia copyrighted TrueType font that would not permit itself to be embedded in a PDF no matter how I tried to create that PDF. The font worked fine within Adobe apps but when it came to creating the PDF, a warning dialog was displayed, even when going through Distiller and the font was replaced by Courier.
As it was just display type, I rendered it as outlines in Illustrator then placed it into my document as an EPS whch then distilled fine.
Or there simply may be something flaky about the encoding on the file itself.
If it's just a short piece of text, could you not find a work-around like creating your piece of typography in Fireworks or another app and then exporting it as a Photoshop-friendly file?
I appreciate you may want that vector crispness if you can create outlines in another app but a bitmap 1200-1800ppi TIFF would also hold up under most circumstances...