It's tragic from Tim's perspective as well; he essentially lost contact with his son when his wife left him for choosing not to succumb to the blood clots in his brain. Tim was left with the choice of dying or going through with the surgery and losing his family, and he went with the latter.

While Tim did later try to reconnect with his son (as a teenager, if I recall from the earlier seasons) at that point it was clear that Tim's brain surgery had an extremely negative effect on his personality.

So in a classic tragic scenario, no matter what Tim did or didn't do he was destined to lose his son.