Bad Font Breaks Time Machine?

So I came across this error in my Mac OS X system.log while performing a Time Machine backup:

backupd[]: Unable to rebuild path cache for source item. Partial source path:

I don’t know about you, but when I see errors from my backup daemon, I pay attention.

I first forced a reindex of Spotlight on the source device by removing the metadata:

sudo hdutil -E /

Spotlight got busy again, but after 20 minutes, I saw log entries along the lines of:

mdworker[]: ATSFontFindFromContainer failed: count = 2

And when I say lines, I mean hundreds of them.  Disk Utility returned OK on both devices, but Spotlight seemed to be spinning its wheels:

mdworker[]: (Error) Import: Importer force killed!

I “validated” the integrity of the fonts in Font Book, only to find csd12.ttf gave a warning.  After removing the font, Spotlight finished indexing in 30 minutes. With no more log errors, Time Machine now seems content to copy my files hour after hour.

So could it be that a bad font caused problems for OS X’s backup mechanism?