Isn't there other LV stuff in the circuit that is being powered either off the HV line or by a separate means. Since you don't mention any I assume all those that exist are safe. Couldn't you just tap power off of that?
If you're really after safety shouldn't you just use a Adum1234? Or an opto-isolator? And an isolated LV supply? Because a resistor that lets by 5mA of high voltage is enough to do harm. Also remember that if the silicon fails short (which silicon seems to do when it does fail), the resistor won't protect you. It just seems to me that having burning off that energy is wasteful and having a resistor running at 80C is a bit needless toowhen a tiny step-down transformer and another diode rectifier would be, be safer, run cooler and be more efficient.