The restriction on 'A4 size' has certainly been in place since that time. I suppose if you had a very small rucksack, it shouldn't be a problem. I think the intention is to prevent people turning up with large hiking rucksacks that would not only cause impracticalities in a crowded stadium but...
Yeh, he's a negative bell end. Go back to 2014 and you'll see moaning at the fact that Bloom had spent 30 odd million of his own cash on the long-term investment of the training ground and academy instead of ignoring FFP rules - which were quite tight at the time - and splurging it on transfer...