How would you do it non-radar? Hint: 91.117(a) applies. Hint: NORDO w/ radar the answer is the same.
What the heck does the 250 knot speed limit have to do with this discussion?
In any event, if you poll every controller in the FAA, and ask them about the filed-through-IAF case, I'll bet virtually all of them
expect you to hold at the IAF when you get there, and not go to over the airport and then back to the IAF. I'll also bet that virtually all of them
want you to commence your approach upon arrival at the IAF, even if your ETE has not yet expired, whether that's what it says in 91.185 or not.
Recognize that
lost comm in IMC is an emergency situation, and that means 91.3(b) says you can deviate from 91.185(c) to the extent necessary to deal with that emergency, i.e., to get the airplane on the ground as soon as you deem necessary, with respect to 91.7(b)'s requirement that when an unairworthy condition occurs in flight you discontinue the fight (and "no comm" is unairworthy for IFR operations -- 91.205(d)(2) refers).
Finally, keep in mind that:
- ATC will be clearing the airspace ahead of and below you, as well as praying that you get on the ground quickly and safely, and
- While the NTSB has burned pilots who keep a sick plane in the air, they have repeatedly said they are very reluctant to second-guess the judgement of a pilot who deviates from the rules to get a sick airplane on the ground expeditiously.
Bottom line: When you've filed via an IAF, and you lose comm in IMC, the fact that the clearance limit is technically the destination airport does not override all other considerations and demand that you blindly fly to the IAF, to the airport, and back to the IAF before holding or commencing the approach without regard to any other fact or regulation.
You're the PIC -- if you get in this situation, make a good decision.