You're putting the cart before the horse there. Which might have been forgivable if the title was just for attention, but it continues throughout your pointless post.
It's not just the gift or receipt of money that is a crime -- obviously not, given how many different folks, companies and other organizations contribute money to political campaigns. It would be the gift and receipt of money in exchange for what I'll call favors - that is, specific governmental actions that would not otherwise have been taken.
So you're taking what is obviously a bunch of public relations stuff -- recipients of money from Abramoff et al, who are "returning" the money donated to their campaigns because of the Abramoff scandal -- and equating it with a legal defense strategy.
In essence, they're attempting to publicly disassociate themselves from Abramoff and his money, lest even the appearance of corruption be attached to them (or lest any journalists attempt to imply guilt on bribery/corruption merely from the existence of a campaign contribution -- but they wouldn't do that, right?). They're politicians, after all, so nothing is more important to them than others' opinions of them -- those are their only stock and trade come election time. BTW, I'll note here that all the politicians that have been named in the press as receiving Abramoff donations have "given them back."
Whether or not the recipients of Abramoff's campaign contributions give them back will have no effect whatsoever on the adjudication of any bribery or corruption charges that may be leveled.
But here you are, assuming guilt in the first instance and misequating PR moves with legal ones.
Anyone who took money from Abramoff in exchange for favors should be thrown under the bus, as it were. But we might at least want to wait until any indictments are filed (or plea bargains made) before assessing (currently non-existent) legal strategies of the defense...
It's interesting to speculate on those who may find trouble as a result of Abramoff's sleaze fest, but this is just ridiculous.