It doesn't come from ICAO.
Here's the story. EUROCONTROL developed a single radio communications failure procedure for the European region and talked ICAO into adopting in on 24 January 2002. It was published in Doc 7030 Regional Supplement and so modifies the procedure in Doc 4444.
The revised procedure was pretty much based on the assumption that radio failures only occur in a radar environment and, maybe because EUROCONTROL is a bit light on aerodrome operations (although I've been castigated when making the suggestion in the past so make up you own mind on the reasons), didn't deal well with all of the possible situations that can occur. Now, although 'delay not determined' is not a common instruction, it would be nice to know what should be done if an aircraft goes radio fail in these rare circumstances so the UK added added the paragraph that Neptune quotes. The reality is that in the circumstances that would require an EAT of 'delay not determined' it is safer for an aircraft to divert somewhere else than to try and land on a runway that was, for some reason, not available when the aircraft approached the fix.
It's important not to take this paragraph out of context. If the rest of the comm failure procedure is followed, ATC will watch closely what the aircraft does and will try to clear everything else out of the way. And the procedures describe a couple of alternative comm channels that might be usable.
Hope this helps. Doc 7030 ref is EUR/RAC 5.0.