I've never understood the defense of Pete Rose.
Here is a man who quite knowingly violated a rule designed to protect baseball against something that has the potential to destroy it. Gambling, unlike any other illicit activity in MLB, changes the goal of any participant from what is the goal of the team into a goal of maximizing monetary gain at the potential expense of winning. This doesn't even include the fact that he thumbed his nose at MLB for the better part of two decades while cultivating a following based on his victim mentality.
People try to excuse his behavior on that he never bet against his team. Assuming that's true, and that is a big assumption given his behavior since then, there are HUGE issues:
1. By not betting on his team on some games, then he personally lowered his stake in those games. This leads to the question of "Did he manage the games he had money on at the expense of the games he didn't?"
2. By indebting himself to bookies, he put himself in a vulnerable position. Now, you have a manager who is in a situation where a quid pro quo may be used: You lose a few games where you're favored, and we'll forgive some or all of the debt.