I would guess that with the lower overall talent level in the CFL, Tebow should be able to play there. While passing may not be his strong suit, it should be strong enough to allow him to play there (and it needs to become a strong suit.) He needs reps in game situations and he needs practice maintaining his improved mechanics while under duress. The CFL could provide that.
A few years ago he was the starter on an NFL playoff team, although I will grant that he was a poor man's Trent Dilfer at the time. He has improved his throwing motion rather dramatically since that time, but he has had very little game action.
I don't buy the persecution angle, but I think he's a lot closer to being good enough than he was when he was actually playing. If he wants to keep trying, Canada could be a good option.
If defenses in the CFL are at college-level talent, Tebow could have a field day. Look at his stats from the final college game he played against Cincinnati in the Sugar Bowl.
But it's still a passing game. Three downs instead of four. Field is 150 yards instead of 100, 65 yards wide instead of 53.5. Twelve players instead of eleven. It's tailored for a passing game and passing is a Tebow weakness. Also he has demonstrated time and again that he problems reading defenses on a smaller field with fewer players. The Canadian game would just make that worse. Tebow doesn't have the level of talent necessry to play in either league.
He has improved his throwing motion rather dramatically since that time, but he has had very little game action.
Tebow's problems go beyond throwing motion. He has shown time and again, by the number of sacks he takes and delay of game penalties he generates, that he has problems reading defenses and making changes at the line of scrimmage. He just doesn't have what it takes, but for that matter few college quarterbacks do. The history of the NFL is filled with QBs who lit it up in college and were complete busts in the NFL. I would not put Tebow in the "complete bust" category. But I do believe he hasn't the necessary talent to compete at the pro level.