Trengove decision certainly makes an argument that the club is a great place to stay for young players, so your point is taken.
At the end of the day, we will never know the true motivation for Tom's decision (well, unlikely anyway). It is his decision though, and we must accept that. I have a feeling his bung knee might be playing a large part in his decision. If my knee was so suspect, it would be hard to turn down a long and well paying contract that guarantees financial security. He might only play 50 games for GWS before it gives way.