If donations is a factor, it would be more logical for politicians to consider the likelihood of future donations rather than past ones. In fact, if the chance of future donations is close to zero, there is a certain appeal in making an example of SBF to "prove" that donations do not matter in this way.
(I'm still mulling whether they do or not; just commenting on the game theory.)
On the other hand it's not good when they embarrass you, regardless of how much they might have put in. If you make it clear that being hung out to dry will be the punishment for embarrassment, maybe you'll get fewer of those donations.
(I'm still mulling whether they do or not; just commenting on the game theory.)