FlightPathOBN makes an important point that all of the rules (from ICAO or wherever) - when taken together - describe how the aviation system works. One must be wary when taking just one sentence or paragraph not to consider how it relates to other parts of the ruleset. However, we can't read all the rules every time we want to find the answer to a question - that's why the rules are written within a relatively simple structure. And we have to use our professional knowledge to recognise when it is necessary to refer to some other rule to get the full answer to our question rather than blindly repeat extracts of text from a book.
And yes, the pilot is always going to be primarily responsible for not letting the aeroplane hit something - but then we need to think about how the rest of the system allows him/her to conduct a flight without anything remiss happening.
bookworm has helpfully told us what PANS-ATM says about the topic -
When vectoring an IFR flight and when giving an IFR flight a direct routing which takes the aircraft off an ATS route, the controller shall issue clearances such that the prescribed obstacle clearance will exist at all times until the aircraft reaches a point where the pilot will resume own navigation.
But nothing in life is simple. Each country has to take the ICAO words and put them into their national rules. Some transpose the words verbatim, some may consider that there is some ambiguity and re-write the rule slightly to make it clearer, and then it often must be translated to the local language which brings its own problems.....
I don't have all of the reference books to hand but it looks like skybrary has re-written the ICAO text (or maybe used one State's interpretation of it) for its article. But it still seems a bit ambiguous because I'm not sure what radar assistance is.
As a rule of thumb I have always worked on the basis that when providing a radar service (even if the aircraft is on its own navigation) I will allocate terrain safe levels. When offering a procedural control service it's the pilot's responsibility to assure terrain clearance. In my experience as an approach controller the practical upshot of this is that when using radar I don't issue a clearance that takes the aircraft below the minimum published level on the charts (whatever they are called these days), and when doing it procedurally I have to allocate a level that is safe at the approach fix (for example) but how the pilot gets there is his or her responsibility. In truth, wherever I have done procedural approach there has been high ground around nearby and I have always given descent to terrain safe levels based on DME ranges 'just in case'.