The title "Chef" Dosent make him edumacated in BBQ
Ive seen some shocker chefs that give wrong advice and some of them famous.
Buc, If you like grilling with Olive oil, Then do so.
I did just that for years until I realised It wasnt "AS GOOD" as other oils.
That is the balls of what was discused here abouts. And If I my memory serves me, It was about a newbie that had bad BLACK sear marks on his beef or chicken steaks.
The recomendation was made to go to a higher flash point oil (And clean his grill) and I belive that did the trick.
That said, And I think this is where your chef info is going awry, Is that some food benifits from olive oil grilling, Like capsican, BUT, That is at a low temp grill.
I still think there are better oils for tha BBQ. Ask your local webber dealer about what they think of it.
It turns to black crud