In my humble opinion it was absolutely the right decision to take a punt on him. The guy clearly has talent as his previous record shows, along with the big fee's paid for his services in the past. At 29, I think most people would think he still has time to prove it. For whatever reason though, his career has gone off the rails in recent years. There are numerous examples in the past of players not performing who have come to a new club and given themselves a new lease of life. Conversely there are plenty for whom it hasn't worked out and they've nose dived into oblivion. I personally see Brodie as falling sadly into the latter case, a player with bags of potential when he was younger, but now tragically unable to cut it in the Conference North.
It hasn't worked out and the manager has acted decisively for which he deserves credit. However, with all that previous potential I don't think you could blame AM for taking a punt on him in the hope of him rediscovering some of his past form. And for what it's worth, just because Colin Davy has been proven right in this case, it doesn't make him correct in judging a player based on watching him for 45 minutes!