This seems to reinforce the mindset that the web should be experienced and built using different tools for users vs. developers, and aside from thinking that's fundamentally condescending, I don't see why new tools couldn't simply be extended from FF's 'web developer' menu into a different mode of operation or even extensions. I think we're better off in a world where kids don't have to install ScaryFox on their tabl…
Is it condescending? Yes. Does it make the barrier to entry in programming higher? Yes, but considering that properly debugging a web application on a tablet seems to require a separate laptop connected at the same time (with admin privileges to install whatever crazy USB drivers), I'd say that barrier is already high enough that the kid can figure out how to download $DEVELOPER_FIREFOX.