The only problem is you can only activate so many leve's at a time , and of a certain class.. max i can reach for a crafter/gathering class is 4 at any given time until i turned them in.
Unless he saved up stacks for 1 leve and activates them over and over again.
I use to make tons of crafts, filling up my inventory for turning in triples , still you have to run up and down to get the leve quest and turn them in to the npc.
Seeing the pic ,i do have my doubts.. looks like a cheat or exploit indeed.
No way he can level up that fast using a lvl 20 leve over and over again to lvl 50 , wich he does because lvl 30 leves arent available/unlocked untill you reach lvl 25