Well, here's the thing, I suggested that he get pushed onto the Grey Wardens by the Chantry because I am not sure if he's the type of guy anyone would trust enough to take with them; he is a smart alec type of guy who cracks jokes like no other and seemingly doesn't take anything seriously enough that I'm pretty sure Faer would be skeptical about letting him come.
But if the Priestess or Priest tell the Grey Wardens to take him, there isn't really much else they could honestly do. There is also the fact that they won't have a Templar and even if he is unorthodox about his duties, he still does them, which will count for something. Plus, he also probably has some experience in fighting that we could use.
Also -- I'm not entirely sure what you mean by 'someone different for Simon'?