If you're cynical enough to believe donating cash to politicians directly buys pardons - then surely you're also cynical enough to realise the politician doesn't have to uphold their end of the bargain.

It's not like SBF is going to be making any big future donations.

Donors hoping for favours know donations only buy so much; the politician takes the money in order to improve their chances of getting elected. If you want a favour which noticeably reduces their chance of getting re-elected - you won't get it.