Una Due Tfc: It's extremely unlikely the RFF guys were using Halon to put an apron fire out, so the comparison is tenuous. Halon use is very restricted these days. It's performance at putting out fires is phenomenal, but its also a greenhouse gas so it only gets used in highly critical situations.
To control a "smoking" suitcase on the apron the fire guys may even have decided not to waste their foam on it -, water alone will achieve the same result it just takes longer. It's not a "critical" situation when its on the apron away from the aircraft.
I used to do some RFF work when I was learning to fly. During a training exercise we ran timed tests to compare the time taken to put out a typical fully developed fire in a light aircraft. With water only it took about 2.5 mins, with foam it took less than 30 seconds. Obviously we didn't test Halon, but I am reliably informed the same test by a competent crew using Halon would be extinguished in less than ten seconds.