Here in So CA, land of "sticks & stucco", these aren't considered to be fireblocks at all. The requirements for blocks are 3 from a corner, and 2 from an opening (door, window, etc). We're required to seal holes in exterior walls (for insulation reasons), but not interior, unless they're through the wall's top or bottom plate.
Since RX isn't rated for any firewall penetrations, I can't remember the issue of firecaulking around it ever coming up.
