Yes, it appears that navaid aerodromes impose greater requirements than non-navaid aerodromes but this is not actually true.
Mmmm, then of course RNAV(GNSS) approaches...
b. For aerodromes with an instrument approach procedure where an aerodrome forecast is unavailable or is "provisional", the pilot in command must make provision for a suitable alternate.
Navigation aid is not even mentioned in that sentence is it?
So dirt strip in the GAFA with an RNAV approach but no TAF WILL REQUIRE an alternate.