"it doesn't say Final Product, it says Mock-ups"

It's still irresponsible to use those images and that layout, after rejecting a bid by that design company to create images and layout for the product, even in a mockup.

It is irresponsible, for sure. But is an appropriate reaction to set up a big witch hunt and publicly shame Mozilla? Is that how businesses and organizations should be treating each other? People make mistakes. Give them a chance to make things right before you try to do damage to someone's reputation.

Would you hold the same opinion if microsoft had done this and not mozilla? (just asking)

Mozilla also recorded and released a lengthy video tutorial portraying and promoting the product, which entirely uses MetaLab's design, with absolutely no indication that the design is only an internal mock-up.

(They have since made the video "private" on Vimeo, though it is still on all of their promotional material.)