Frankly, I wish I was surprised. Realistically is was only a matter of time before this happened, and once it was clear that bringing Firefox to PPC MacOS wasn't going to be a matter of a straight port, the righting was already on the wall. The SSL Apocalypse was just another piece of that writing on that wall, too.
So, if anything, we need to thank Cameron for supporting this project for as long as he did. Given what the engine is based on, it was always going to start breaking at some point. We're all better off to know that he's ending mainline support, rather than have him just vanish.
And while we're at it, an update to Classilla is absolutely welcome.
I do feel this is a probably a good and clear sign that it's time to move forward if you use a PowerPC Mac as a main computer. That doesn't mean it all suddenly becomes useless, or that you aren't going to be able to browse the internet tomorrow, but it's just going to get worse from here.