the FreeBSD devil is so cutesy I find it hard to believe someone would be that offended. And it's not like "the devil" is some sort of huge taboo in the US, it is often used in relatively benign product's names.
Some example "demonic" products off the top of my head
I think some fundies would have a problem with it specifically because it's cutesy - I remember reading people being anti Harry Potter because it trivialized what they saw as black, satanic magic
To be fair, though, they would have an even bigger problem with it if it wasn't cutesy. They have a problem with it because they believe it's satanic, not because it's cutesy.
Take your Harry Potter example. The people who are anti-Harry Potter aren't really against it because it trivializes black magic. That's just a rationalization. These people certainly don't support something like the works of Aleister Crowley, even though they're much more serious about their treatment of the occult. They're against it because it contains -- in their view -- black, satanic magic.
Some example "demonic" products off the top of my head
- New Jersey Devils (NHL team)
- Dirt Devil (a vacuum)
- Devil's food cake (a popular dessert)