I see a very good reason to join the TA, There may not be any 'bushcraft' involved, (apart from doing various survival courses and E&E) however knowing josh personally it would be a very good idea for him to join since he will learn other skills like campcraft, structure, discipline, fitness, navigation, first aid, actually living in the fieild and going on empty. I think it would be better for him than the scouts as the scouts are mainly children and therefore less maturity in general would be involved with the scouts. Also there are numerous adventure taining courses and instructor courses you get to go on all for free. Far better than any scout unit could even dream about doing.
Davey, you have some valid points but the Scouts shouldn't be dismissed so quickly. They want to teach. If they become a Scout Leader, they will gain a different type of experience that they won't get from the TA - kids and immaturity. It is a big challenge trying to teach Scouts.
It would actually be quite a good idea to join a Scout group as a bit of a work experience taster to see if they actually do want to teach.