Unlikely. We've watched the kites at Watlington on several occasions. Even when some bait was put down in the middle of the large rally field by a photographer wanting a shot (all tents around the edge and no one crossing the middle) the kites circled for a long time, and about two dozen had gathered. After a while, they started circling lower, and this went on for a while, too. When the first one dived, it missed, but that had precipitated dives by many of the birds, and the second or third got most of the prize.
It took over 15 minutes from bait laid to a bird getting it. And Watlington is said to be where the kites are most tame. I am extremely sceptical about reports of meat being snatched from barbecues.