wrote:

Roy thinks "when able direct" implies the controller is assuming
responsibility for terrain clearance.

Absolutely he does. A controller never says to proceed direct when
able, when the "when able" part means that you have to know when you are
above the terrain. When able direct always means navigation. When you
are receiving the relavant station you may go directly to it.


bob suggests "when able direct" implies the pilot, not the controller
is assuming responsibility for terrain clearance.

That's not correct.