There is a reference in ICAO but I think it is only in the R/T section.
However, from a pilot's point of view this is very simply how the situation works;
1. Aircraft A arrives at the holding fix and requires to hold awaiting weather improvement. ICAO simply says move that aircraft to another hold or to the top of the stack so that other aircraft who can make an approach are not delayed. Thus there should not be a case where aircraft who can make an approach (and be given an EAT if necessary) are above aircraft who can not.
2. If the weather is such that all the aircraft in the stack are holding awaiting an improvement then everyone gets "delay not determined"
If the weather is below minima you can not start an approach (legal requirement). If you have a radio failure before hearing that the weather has improved sufficiently to make an approach there is nothing else to do other than divert.
The same goes if say the runway is blocked........you arrive at the top of the stack and get delay not determined due runway blocked. If you then get an R/T failure why would you waste fuel making an approach to (according to the latest info you have) a U/S runway?
Let me see.......with 3 VHF comms, HF, ACARS, Satcom and a trusty mobile.......if we have a total communication failure we are really in the pooooooooo..............probably for reasons other than communication!
Regards,
DFC