I would say he should not turn on to the LLZ track using his GPS unless he is cleared for an Approved GPS Approach.
From what you say, it seems it was not a GPS Approach but an ordinary ILS Approach.
Clearly, if he is on a heading for LOC intercept, the only turn should be on to the Localiser beam itself i.e. at ILS LOC capture. To anticipate this turn for any other reason than an active beam bar would be, to use your words, just "poor airmanship".
JD
