Keg, I'm not defending it, just telling it as it is. And as for it not being in accordance with the supp you need to read the rest of the para (my bolding):
"When traffic delays for these locations are expected to exceed these times, and in any case when significant traffic delays at other aerodromes are anticipated, ATC will advise the holding time by NOTAM"
The excessive delays were neither expected nor anticipated. Something changed and caused them to blow out.
I don't know how long the process takes to run the numbers and generate a new holding NOTAM or even if it can handle using live traffic as a starting point. It's certainly not instantaneous & isn't triggered automatically.