No SID in clearance, fly it anyway?

To add some controller input for the position that a heading is not a
vector, here is a post from a controller in another online aviation
forum:

-----------------snip-------------------------------
From a radar controllers' perspective, there is no such thing as a
radar vector when in a non radar environemnt, this mean if you don't
hear radar contact first, then any assigned heading prior to those
words does not constitute a vector. A radar vector is course guidance
predicated on radar. Simply by launching from the surface on a
assigned heading must not be construed as a radar vector.

We assign an initial heading to fly from all our towered fields, and
that is all they are, until you hear radar contact and then receive a
subsequent heading. Then and only then is a radar vector in play.
....
my concern here is that many pilots assume that when a heading is
assigned off the ground by a tower controller where there is a surface
area, that it is automatically controller assuming terrain and
obstacle clearance, it is not. The pilot assumes this responsibility
until reaching a minimum IFR altitude or the controller provides a
subsequent heading once airborne whether at or below the Minimum IFR
altitude. The rationale for this is that the 40:1 is reviewed or
there is a ODP for the pilot to fly at his/her perogotive.
-----------------snip-------------------------------