It may be illegal but he's accepting it! I did it a fair few years ago and tbh glasto, download, v-festival, oxegen, etc it's not about the money, you do a 12hr shift, have a laugh, then during your downtime you've got free entry and access all areas to some of the best festivals this country has to offer, not to mention (company dependant) you get two free meals a day. £50 for 12hrs a rip maybe, but then look at the price of glasto tickets.
On another note, why does it have to be straight onto the doors? Just call round all the local companies, get on sites, then soon enough either his own company will offer him door work once he's proved himself reliable and trustworthy or by working sites he'll start meeting and making friends with his colleagues who will then start thinking of him when they find work being offered to them and they'll refer him and hey presto!