Indeed, Dr, Triax, communication and navigation radio coverage is NOT considered, in TERPS anyway, for the MSA calculations.
HEATHROW DIRECTOR, in FAAO 7110.65, I don't believe a controller can send a plane direct to the FAF with the intention of intercepting final at the FAF; the plane be vectored must be on a vector to intercept final at least 3 nm from the FAF at the minimum altitude for the approach.
GF