Thanks for the helpful responses and highlighting the DC issue. It's not something I was aware of.
I'm not using this specific design, but am working on a similar circuit (mains -> 5VDC buck with a half-wave rect.), but avg output is only 50mW, so it would be difficult to hit 5mA avg on the input, even with a terrible power factor, although as you say probably better to have a full rectifier anyway, and likely cheaper given reduced bulk input caps.
My inductor is 500VAC rated.
RF1 is non-flammable fuseable type, but my point was that the current required to break the fuse would have long since turned the 220R resistors into smoke, although I guess it's not impossible that they could fail short.