I agree that as far as his personality and abilities are concerned he would be unsuitable for the kind of life his mother and sister have mapped out for him, and we are told by Austen that it was not in his power to go completely against his mothers wishes, "the whole of his fortune depended on the will of his mother". And yet he seems to be his own kind of person in spite of this,"Edward had no turn for great men or barouches". He certainly is very different to Fanny-a quality which seems to recommend him to Elinor and her Mother. While he may not be defying his mother outright he certainly isn't going to bullied into a profession he is adverse to.