There's no reason they'd have to be down for two weeks in that case. They could use a binary distribution to immediately get back into shape, and then switch over after compilation's finished, or they could compile without -OX and it'd take almost nothing, and then they'd be good to go.

Really, though, nowadays compiling everything, even compiling things for optimal performance, doesn't take that long. Your production machines shouldn't have web browsers, and without the C++ garbage behemoths on it, compilation takes like half an hour on most machines.

I'm not a Gentoo user, but it's kind of silly to act like it makes recovering substantially harder than any other distribution.

This was at a time when compiling just the kernel took 30 minutes, so YMMV. But obviously, I don't know. Just didn't seem to me like the choice is want to make for running a business. Again, ymmv...

I imagine anyone doing this seriously would have a spearate system for building binaries. Obviously if that system was compromised, you would not be in a great situation, but it should be much easire to lock that down.