[rahimnathwani]

As I understand it, it would permitted for Dell to build their own binary from source (having previously changed any mention of Firefox to something else), and to charge for that software.

The issue is that, by using the binary, which contains a Mozilla-owned trademark, they become subject to Mozilla's trademark policy.

IANAL, and am curious: What binds Dell to adhere to Mozilla's trademark policy? They are not using the Firefox trademark in a way which is likely to cause confusion (assuming they are using the official binary) or to devalue the Firefox brand. (How) can a trademark-owner go about adding their own conditions to the use of a trademark, over and above those provided for by trademark law?

[joveian]

It is devaluing the brand. Basically Dell is trying to earn easy money off of the name Firefox being well known. Some customers may just recognize the name and assume that the charge is reasonable, not knowing that they could easily install it for free. When they find out what is going on, they can easily say things like "Firefox is a scam" without further context, which hurts Firefox.